Multiple network allocation vector operation

ABSTRACT

A first wireless device may determine a bandwidth for transmitting a frame, calculate two or more Spatial Reuse (SR) parameter values for the bandwidth, set, using the SR parameter values, first and second SR fields of the frame based on the bandwidth and a channel center frequency in which the bandwidth is carried, and transmit the frame to a second wireless device on the bandwidth. The first and second SR fields may be set to a first value when the bandwidth is a 40 MHz bandwidth and the channel center frequency is in a 2.4 GHz band. The first and second SR fields may be set to the first value when the bandwidth is an 80+80 MHz bandwidth and the channel center frequency is in a 5 GHz band. The first value may be a minimum of SR parameter values for first and second bandwidths in the bandwidth.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/393,084, filed on Dec. 28, 2016, which claims the benefit of U.S.Provisional Patent Application No. 62/272,033, filed Dec. 28, 2015, U.S.Provisional Patent Application No. 62/355,252 filed Jun. 27, 2016, U.S.Provisional Patent Application No. 62/356,445 filed Jun. 29, 2016, andU.S. Provisional Patent Application No. 62/357,855 filed Jul. 1, 2016,which are incorporated by reference herein in their entireties.

BACKGROUND 1. Technical Field

The technology described herein relates generally to wirelessnetworking. More particularly, the technology relates to efficient useof a shared wireless medium in areas where Wireless Local Area Networks(WLANs) overlap.

2. Description of the Related Art

Wireless LAN (WLAN) devices are currently being deployed in diverseenvironments. Some of these environments have large numbers of accesspoints (APs) and non-AP stations in geographically limited areas. Inaddition, WLAN devices are increasingly required to support a variety ofapplications such as video, cloud access, and offloading. In particular,video traffic is expected to be the dominant type of traffic in manyhigh efficiency WLAN deployments. With the real-time requirements ofsome of these applications, WLAN users demand improved performance indelivering their applications, including improved power consumption forbattery-operated devices.

A WLAN is being standardized by the IEEE (Institute of Electrical andElectronics Engineers) Part 11 under the name of “Wireless LAN MediumAccess Control (MAC) and Physical Layer (PHY) Specifications.” A seriesof standards have been adopted as the WLAN evolved, including IEEE Std802.11™-2012 (March 2012) (IEEE 802.11n). The IEEE Std 802.11 wassubsequently amended by IEEE Std 802.11ae™-2012, IEEE Std802.11aa™-2012, IEEE Std 802.11ad™-2012, and IEEE Std 802.11ac™-2013(IEEE 802.11ac).

Recently, an amendment focused on providing a High Efficiency (HE) WLANin high-density scenarios is being developed by the IEEE 802.11ax taskgroup. The 802.11ax amendment focuses on improving metrics that reflectuser experience, such as average per station throughput, the 5thpercentile of per station throughput of a group of stations, and areathroughput. Improvements may be made to support environments such aswireless corporate offices, outdoor hotspots, dense residentialapartments, and stadiums.

Where WLANs overlap, communications in one WLAN may preventcommunications in another WLAN. When this causes WLAN communications tobe prevented unnecessarily, system efficiency of the WLANs is decreased.

SUMMARY

In an embodiment, a method is performed by a first wireless device. Themethod comprises determining, by the first wireless device, a bandwidthon which a frame will be transmitted to a second wireless device,calculating, by the first wireless device, two or more Spatial Reuse(SR) parameter values for the bandwidth, setting, by the first wirelessdevice using the two or more SR parameter values, a first SR field and asecond SR field of the frame based on the bandwidth and a channel centerfrequency in which the bandwidth is carried, and transmitting the frameto the second wireless device on the bandwidth.

In an embodiment, the method further comprises setting the first SRfield and the second SR field to a first SR value when the bandwidth isa 40 MHz bandwidth and the channel center frequency is in a 2.4 GHzband.

In an embodiment, the method further comprises setting a third SR fieldof the frame to the first SR value, and setting a fourth SR field of theframe to the first SR value when the bandwidth is the 40 MHz bandwidthand the channel center frequency is in a 2.4 GHz band.

In an embodiment, calculating the two or more SR parameter values whenthe bandwidth is the 40 MHz bandwidth and the channel center frequencyis in the 2.4 GHz band comprises determining a first SR parameter valuefor a first 20 MHz in the bandwidth, determining a second SR parametervalue for a second 20 MHz in the bandwidth, setting the first SR valueto a minimum of the first SR parameter value and the second SR parametervalue when the bandwidth is the 40 MHz bandwidth and the channel centerfrequency is in the 2.4 GHz band.

In an embodiment, the method further comprises setting the first SRfield to the first SR value when the bandwidth is an 80+80 MHz bandwidthand the channel center frequency is in a 5 GHz band, and setting thesecond SR field to the second SR value when the bandwidth is an 80+80MHz bandwidth and the channel center frequency is in the 5 GHz band.

In an embodiment, the method further comprises setting a third SR fieldof the frame to the first SR value when the bandwidth is the 80+80 MHzbandwidth and the channel center frequency is in the 5 GHz band, settinga fourth SR field of the frame to the second SR value when the bandwidthis the 80+80 MHz bandwidth and the channel center frequency is in the 5GHz band.

In an embodiment, calculating the two or more SR parameter values whenthe bandwidth is the 80+80 MHz bandwidth and the channel centerfrequency is in a 5 GHz band comprises determining a first SR parametervalue, in the two or more SR parameter values, for a first 40 MHz of thebandwidth, determining a second SR parameter value, in the two or moreSR parameter values, for a second 40 MHz of the bandwidth, determining athird SR parameter value, in the two or more SR parameter values, for athird 40 MHz of the bandwidth, determining a fourth SR parameter value,in the two or more SR parameter values, for a fourth 40 MHz of thebandwidth, setting the first SR value to a minimum of the first SRparameter value and the third SR parameter value when the bandwidth isthe 80+80 MHz bandwidth and the channel center frequency is in the 5 GHzband, and setting the second SR value to a minimum of the second SRparameter value and the fourth SR parameter value when the bandwidth isthe 80+80 MHz bandwidth and the channel center frequency is in the 5 GHzband.

In an embodiment, the first SR field has a length of four bits and thesecond SR field has a length of four bits.

In an embodiment, the frame is a Trigger frame.

In an embodiment, a method is performed by a wireless device. The methodcomprises determining, by the wireless device, an operational bandwidthof a frame to be transmitted, calculating, by the wireless device, aplurality of Spatial Reuse (SR) parameter values for the operationalbandwidth, and setting, by the wireless device using the plurality of SRparameters, first and second fields of a frame according to theoperational bandwidth and a channel center frequency. The first andsecond fields including information for use in a Spatial Reuse (SR)operation. The method further comprises transmitting the frame using thechannel center frequency and on the operational bandwidth.

In an embodiment, the frame is a Trigger frame, and the operationalbandwidth is an operational bandwidth of a Physical Protocol Data Unit(PPDU) transmitted in response to the Trigger frame.

In an embodiment, the method further comprises setting the first fieldand the second field to a first value when the operational bandwidth isa 40 MHz bandwidth and the channel center frequency is in a 2.4 GHzband.

In an embodiment, the method further comprises setting a third field ofthe frame to the first value, the third field including information foruse in the SR operation, and setting a fourth field of the frame to thefirst value when the bandwidth is a 40 MHz bandwidth and the channelcenter frequency is in the 2.4 GHz band, the fourth field includesinformation for use in the SR operation.

In an embodiment, calculating the plurality of SR parameter valuescomprises determining a first SR parameter value of the plurality of SRparameter values for a first 20 MHz bandwidth, determining a second SRparameter value of the plurality of SR parameter values for a second 20MHz bandwidth, and setting the first value to a minimum of the first SRparameter value and the second SR parameter value when the bandwidth isthe 40 MHz bandwidth and the channel center frequency is in the 2.4 GHzband.

In an embodiment, the method further comprises setting the first fieldto a first value when the bandwidth is an 80+80 MHz bandwidth and thechannel center frequency is in a 5 GHz band; and setting the secondfield to a second value when the bandwidth is the 80+80 MHz bandwidthand the channel center frequency is in the 5 GHz band.

In an embodiment, the method further comprises setting a third field ofthe frame to the first value, and setting a fourth field of the frame tothe second value when the bandwidth is the 80+80 MHz bandwidth and thechannel center frequency is in the 5 GHz band.

In an embodiment, calculating the plurality of Spatial Reuse (SR)parameter values comprises determining a first SR parameter value of theplurality of SR parameter values for a first 40 MHz bandwidth of theoperational bandwidth, determining a second SR parameter value of theplurality of SR parameter values for a second 40 MHz bandwidth of theoperational bandwidth, determining a third SR parameter value of theplurality of SR parameter values for a third 40 MHz bandwidth of theoperational bandwidth, determining a fourth SR parameter value of theplurality of SR parameter values for a fourth 40 MHz bandwidth of theoperational bandwidth, setting the first value to a minimum of the firstSR parameter and the third SR parameter when the bandwidth is the 80+80MHz bandwidth and the channel center frequency is in the 5 GHz band, andsetting the second value to a minimum of the second SR parameter and thefourth SR parameter when the bandwidth is the 80+80 MHz bandwidth andthe channel center frequency is in the 5 GHz band.

In an embodiment, the first field has a length of four bits and thesecond field has a length of four bits.

In an embodiment, the first field corresponds to a signal power and thesecond field corresponds to a signal power.

In an embodiment, a first wireless device comprises one or moreprocessors and a transmitter circuit. The first wireless devicedetermines, using the one or more processors, a bandwidth on which aframe will be transmitted to a second wireless device, calculates, usingthe one or more processors, two or more Spatial Reuse (SR) parametervalues for the bandwidth, sets, using the one or more processors and thetwo or more SR parameter values, a first SR field and a second SR fieldof the frame based on the bandwidth and a channel center frequency onwhich the bandwidth is carried, and transmits, using the transmittercircuit, the frame to the second wireless device on the bandwidth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates wireless networks, according to an embodiment.

FIG. 2 is a schematic diagram of a wireless device, according to anembodiment.

FIG. 3A illustrates components of a wireless device configured totransmit data, according to an embodiment.

FIG. 3B illustrates components of a wireless device configured toreceive data, according to an embodiment.

FIG. 4 illustrates Inter-Frame Space (IFS) relationships.

FIG. 5 illustrates a Carrier Sense Multiple Access/Collision Avoidance(CSMA/CA) based frame transmission procedure.

FIG. 6A illustrates a HE PHY Protocol Data Units (PPDU), according to anembodiment.

FIG. 6B shows a Table 1 disclosing additional properties of fields ofthe HE PPDU frame of FIG. 6A, according to an embodiment.

FIG. 7 illustrates a Basic Service Set (BSS) Load element, according toan embodiment.

FIG. 8 illustrates an unassociated station in an Overlapping BasicService Set (OBSS) area where two WLANs overlap, according to anembodiment.

FIG. 9 illustrates a measurement of a channel busy time of an inter-BSSframe according to an embodiment.

FIG. 10 illustrates sensing the medium as busy based on only SpatialReuse (SR) enabled capability, according to an embodiment.

FIG. 11 illustrates sensing the medium as busy based on only SR disabledcapability, according to an embodiment.

FIG. 12 further illustrates a Spatial Reuses operation, according to anembodiment.

FIG. 13 illustrates a frame format for a Trigger frame suitable for usein a High Efficiency (HE) WLAN, according to an embodiment.

FIG. 14 includes a Table 2 showing values of a Cyclic Prefix (CP) andLong Training Field (LTF) field of a Trigger frame, according to anembodiment.

FIG. 15 includes a Table 3 showing values of a Trigger type field of aTrigger frame, according to an embodiment.

FIG. 16 includes a Table 4 showing values of 7-bit indices of a ResourceUnit (RU) Allocation field of a Trigger frame, according to anembodiment.

FIG. 17 illustrates a process for determining whether to perform an SRtransmission based on an OBSS_PD threshold level, according to anembodiment.

FIGS. 18A and 18B illustrate an SR transmission, according to anembodiment.

FIGS. 19A and 19B illustrate an operation of an Opportunistic AdaptiveClear Channel Assessment (OA-CCA) mechanism, according to an embodiment.

FIG. 20 illustrates an issue related to OA-CCA, specifically with regardto operations in a 2.4 GHz band/channel center frequency.

FIG. 21 shows an example of an issue related to OA-CCA in a 5 GHz band.

FIG. 22 shows another example of an issue related to OA-CCA in a 5 GHzband.

FIG. 23 illustrates fields in an HE-SIG-A field related to SpatialReuse, according to an embodiment.

FIG. 24 illustrates an example of SR operation in a 2.4 GHz band,according to an embodiment.

FIG. 25 illustrates another example of SR operation in a 5 GHz band,according to an embodiment.

FIG. 26 illustrates another example of SR operation in a 5 GHz band,according to an embodiment.

FIG. 27 illustrates values of SR fields within an HE-SIG-A field of anUL Trigger-based PPDU, according to an embodiment.

FIG. 28 illustrates the SR values used for SR transmissions, accordingto an embodiment.

FIG. 29 illustrates aspects of OA_CCA for a 40 MHz transmission having achannel center frequency in a 2.4 GHz band, according to an embodiment.

FIG. 30 illustrates aspects of OA_CCA for an 80+80 MHz transmission on achannel center frequency in a 5 GHz band, according to an embodiment.

FIG. 31 illustrates SR field values of a Trigger frame, according toanother embodiment.

FIG. 32 illustrates SR fields and an optional channel information fieldof an HE-SIG-A field for transmissions in a 2.4 GHz band, according toan embodiment.

FIG. 33 illustrates SR fields and an optional channel information fieldof an HE-SIG-A field for transmissions in a 5 GHz band, according toanother embodiment.

FIG. 34 illustrates SR fields of an HE-SIG-A field for transmissions ina 5 GHz band, according to another embodiment.

FIG. 35 illustrates SR fields of an HE-SIG-A field for transmissions ina 5 GHz band, according to another embodiment.

FIG. 36 illustrates a set of allowed channel bondings which may includethe most useful cases which are most likely to occur, according to anembodiment.

FIGS. 37A and 37B show examples of numberings of 20 MHz bandwidths indiscontinuous 60 MHz channels, according to an embodiment.

FIGS. 38A and 38B show examples of numberings of 20 MHz bandwidths indiscontinuous 60 MHz channels, according to another embodiment.

FIG. 39 illustrates fields in an HE-SIG-A field related to SpatialReuse, according to an embodiment.

FIG. 40 illustrates 80 MHz channelizations of a 5 GHz band as defined inthe United State.

FIG. 41 illustrates a numbering of 80 MHz channelization of a 5 GHz bandas defined in the United State, according to an embodiment.

FIG. 42 illustrates a process for determining SR fields of a Triggerframe, according to an embodiment.

DETAILED DESCRIPTION

The technology described herein relates generally to wirelessnetworking. More particularly, the technology relates to improving theefficiency of a WLAN in situations where a plurality of Basic ServiceSets (BSSs) have overlapping coverage areas (that is, where a pluralityof BSSs overlap), and in particular when one or more stations are in theOverlapping BSS (OBSS) area.

In the following detailed description, certain illustrative embodimentshave been illustrated and described. As those skilled in the art wouldrealize, these embodiments are capable of modification in variousdifferent ways without departing from the scope of the presentdisclosure. Accordingly, the drawings and description are to be regardedas illustrative in nature and not restrictive. Like reference numeralsdesignate like elements in the specification.

FIG. 1 illustrates wireless networks according to an embodiment. Thewireless networks includes first and second infrastructure Basic ServiceSets (BSSs) 100 and 120 of Wireless Local Area Networks (WLANs). In an802.11 WLAN, the BSS provides the basic organizational unit andtypically includes an Access Point (AP) and one or more associatedstations (STAs).

The first BSS 100 includes a first Access Point 102 (also referred to asAP1) wirelessly communicating with first, second, third, and fourthwireless devices (or stations) 104, 106, 108, and 110 (also referred toas stations STA1, STA2, STA3, and STA4, respectively). The second BSS120 includes a second AP 122 (also referred to as AP2) and a fifthdevice (or station) 124 (also referred to as station STA5). The wirelessdevices may each include a medium access control (MAC) layer and aphysical (PHY) layer according to an IEEE 802.11 standard.

Although FIG. 1 shows the first BSS 100 including only the first tofourth stations STA1 to STA4 and the second BSS 120 including only thefifth station STA5, embodiments are not limited thereto and may compriseBSSs including any number of stations.

The first AP 102 is a station, that is, a STA, configured to control andcoordinate functions of the BSS 100. The first AP 102 may transmitinformation to a single station selected from the plurality of stationsSTA1 to STA4 in the first BSS 100 using a single frame, or maysimultaneously transmit information to two or more of the stations STA1to STA4 in the first BSS 100 using either a single Orthogonal FrequencyDivision Multiplexing (OFDM) broadcast frame, a single OFDM Multi-UserMulti-Input-Multi-Output (MU-MIMO) transmission, a single OrthogonalFrequency Division Multiple Access (OFDMA) frame, or a single MU-MIMOOFDMA frame.

The stations STA1 to STA4 may each transmit data to the first AP 102using a single frame, or transmit information to and receive informationfrom each other using a single frame. Two or more of the stations STA1to STA4 may simultaneously transmit data to the first AP 102 using anUplink (UL) OFDMA frame, an UL MU-MIMO frame, or an UL MU-MIMO OFDMAframe.

In another embodiment, the first AP 102 may be absent and the stationsSTA1 to STA4 may be in an ad-hoc network.

The second AP 122 is a station configured to control and coordinatefunctions of the second BSS 120. The second AP 122 may transmitinformation to the fifth station STA5 in the second BSS 120 using asingle frame, or may simultaneously transmit information to two or morestations (not shown) of the second BSS 120 using either a single OFDMbroadcast frame, a single OFDM MU-MIMO transmission, a single OFDMAframe, or a single MU-MIMO OFDMA frame.

The fifth station STA5 may transmit data to the second AP 122 using asingle frame. Two or more of the stations (not shown) of the second BSS120 may simultaneously transmit data to the second AP 122 using anUplink (UL) OFDMA frame, an UL MU-MIMO frame, or an UL MU-MIMO OFDMAframe.

FIG. 1 shows a first intra-BSS Down-Link (DL) transmission 114 and afirst intra-BSS Up-Link (UL) transmission 112 of the first BSS 100, andshows a second intra-BSS DL transmission 126 and a second intra-BSS ULtransmission 128 of the second BSS 120. Intra-BSS transmissions aretransmissions between an AP and stations associated with the BSS thatthe AP controls or between two stations associated with the same BSS.

FIG. 1 also shows first and second inter-BSS transmissions 128-i and126-i. Inter-BSS transmissions are transmissions transmitted by an AP orstation of one BSS and received/detected by an AP or station of anotherBSS. Here, the first inter-BSS transmission 128-i is an interferingtransmission, received by but not targeted/addressed to the thirdstation STA3 associated with the first BSS 100, that was produced as aresult of the transmission of the second intra-BSS UL transmission 128by the fifth station STA5 associated with the second BSS 120. The secondinter-BSS transmission 126-i is an interfering transmission, received bybut not targeted/addressed to the fourth station STA4 associated withthe first BSS 100, that was produced as a result of the transmission ofthe second intra-BSS DL transmission 126 by the second AP 122 thatcontrols the second BSS 120.

The third and fourth stations STA3 and STA4 are located in anOverlapping BSS (OBSS) area 140 of the first and second BSSs 100 and120. Stations in the OBSS area 140 may receive transmission from bothdevices associated with the first BSS 100 and devices associated withthe second BSS 120. Transmissions of the stations in the OBSS area 140may also interfere with transmissions of both the first BSS 100 and thesecond BSS 120 under some circumstances.

Each of the stations STA1 to STA5 and the APs 102 and 122 includes aprocessor and a transceiver, and may further include a user interfaceand a display device.

The processor is configured to generate a frame to be transmittedthrough a wireless network, to process a frame received through thewireless network, and to execute protocols of the wireless network. Theprocessor may perform some or all of its functions by executing computerprogramming instructions stored on a non-transitory computer-readablemedium.

The transceiver represents a unit functionally connected to theprocessor, and designed to transmit and receive a frame through thewireless network. The transceiver may include a single component thatperforms the functions of transmitting and receiving, or two separatecomponents each performing one of such functions.

The processor and transceiver of the stations STA1 to STA5, the first AP102, and the second AP 122 may be respectively implemented usinghardware components, software components, or both.

The first and second APs 102 and 122 may each be or include a WLANrouter, a stand-alone Access Point, a WLAN bridge, a Light-Weight AccessPoint (LWAP) managed by a WLAN controller, and the like. In addition, adevice such as a personal computer, tablet computer, or cellular phonemay configured to be able to operate as the first or second APs 102 or122, such as when a cellular phone is configured to operate as awireless “hot spot.”

Each of the stations STA1 to STA5 may be or may include a desktopcomputer, a laptop computer, a tablet PC, a wireless phone, a mobilephone, a smart phone, an e-book reader, a Portable Multimedia Player(PMP), a portable game console, a navigation system, a digital camera, aDigital Multimedia Broadcasting (DMB) player, a digital audio recorder,a digital audio player, a digital picture recorder, a digital pictureplayer, a digital video recorder, a digital video player, and the like.

The present disclosure may be applied to WLAN systems according to IEEE802.11 standards but embodiments are not limited thereto.

In IEEE 802.11 standards, frames exchanged between stations (includingaccess points) are classified into management frames, control frames,and data frames. A management frame may be a frame used for exchangingmanagement information that is not forwarded to a higher layer of acommunication protocol stack. A control frame may be a frame used forcontrolling access to a medium. A data frame may be a frame used fortransmitting data to be forwarded to the higher layer of thecommunication protocol stack.

A type and subtype of a frame may be identified using a type fieldand/or a subtype field included in a control field of the frame, asprescribed in the applicable standard.

FIG. 2 illustrates a schematic block diagram of a wireless device 200according to an embodiment. The wireless or WLAN device 200 may beincluded in the APs 102 or 122 or any of the stations STA1 to STA5 inFIG. 1. The WLAN device 200 includes a baseband processor 210, a radiofrequency (RF) transceiver 240, an antenna unit 250, a storage device(e.g., memory) 232, one or more input interfaces 234, and one or moreoutput interfaces 236. The baseband processor 210, the memory 232, theinput interfaces 234, the output interfaces 236, and the RF transceiver240 may communicate with each other via a bus 260.

The baseband processor 210 performs baseband signal processing, andincludes a MAC processor 212 and a PHY processor 222. The basebandprocessor 210 may utilize the memory 232, which may include anon-transitory computer readable medium having software (e.g., computerprograming instructions) and data stored therein.

In an embodiment, the MAC processor 212 includes a MAC softwareprocessing unit 214 and a MAC hardware processing unit 216. The MACsoftware processing unit 214 may implement a first plurality offunctions of the MAC layer by executing MAC software, which may beincluded in the software stored in the memory 232. The MAC hardwareprocessing unit 216 may implement a second plurality of functions of theMAC layer in special-purpose hardware. However, the MAC processor 212 isnot limited thereto. For example, the MAC processor 212 may beconfigured to perform the first and second plurality of functionsentirely in software or entirely in hardware according to animplementation.

The PHY processor 222 includes a transmitting signal processing unit(SPU) 224 and a receiving SPU 226. The PHY processor 222 implements aplurality of functions of the PHY layer. These functions may beperformed in software, hardware, or a combination thereof according toan implementation.

Functions performed by the transmitting SPU 224 may include one or moreof Forward Error Correction (FEC) encoding, stream parsing into one ormore spatial streams, diversity encoding of the spatial streams into aplurality of space-time streams, spatial mapping of the space-timestreams to transmit chains, inverse Fourier Transform (iFT) computation,Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and thelike. Functions performed by the receiving SPU 226 may include inversesof the functions performed by the transmitting SPU 224, such as GIremoval, Fourier Transform computation, and the like.

The RF transceiver 240 includes an RF transmitter 242 and an RF receiver244. The RF transceiver 240 is configured to transmit first informationreceived from the baseband processor 210 to the WLAN, and provide secondinformation received from the WLAN to the baseband processor 210.

The antenna unit 250 includes one or more antennas. When Multiple-InputMultiple-Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, the antennaunit 250 may include a plurality of antennas. In an embodiment, theantennas in the antenna unit 250 may operate as a beam-formed antennaarray. In an embodiment, the antennas in the antenna unit 250 may bedirectional antennas, which may be fixed or steerable.

The input interfaces 234 receive information from a user, and the outputinterfaces 236 output information to the user. The input interfaces 234may include one or more of a keyboard, keypad, mouse, touchscreen,microphone, and the like. The output interfaces 236 may include one ormore of a display device, touch screen, speaker, and the like.

As described herein, many functions of the WLAN device 200 may beimplemented in either hardware or software. Which functions areimplemented in software and which functions are implemented in hardwarewill vary according to constraints imposed on a design. The constraintsmay include one or more of design cost, manufacturing cost, time tomarket, power consumption, available semiconductor technology, and soon.

As described herein, a wide variety of electronic devices, circuits,firmware, software, and combinations thereof may be used to implementthe functions of the components of the WLAN device 200. Furthermore, theWLAN device 200 may include other components, such as applicationprocessors, storage interfaces, clock generator circuits, power supplycircuits, and the like, which have been omitted in the interest ofbrevity.

FIG. 3A illustrates components of a wireless device configured totransmit data according to an embodiment, including a Transmitting (Tx)SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In anembodiment, the TxSP 324, the RF transmitter 342, and the antenna 352correspond to the transmitting SPU 224, the RF transmitter 242, and anantenna of the antenna unit 250 of FIG. 2, respectively.

The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304,an inverse Fourier transformer (IFT) 306, and a guard interval (GI)inserter 308.

The encoder 300 receives and encodes input data DATA. In an embodiment,the encoder 300 includes a forward error correction (FEC) encoder. TheFEC encoder may include a binary convolutional code (BCC) encoderfollowed by a puncturing device. The FEC encoder may include alow-density parity-check (LDPC) encoder.

The TxSP 324 may further include a scrambler for scrambling the inputdata before the encoding is performed by the encoder 300 to reduce theprobability of long sequences of 0s or 1s. When the encoder 300 performsthe BCC encoding, the TxSP 324 may further include an encoder parser fordemultiplexing the scrambled bits among a plurality of BCC encoders. IfLDPC encoding is used in the encoder, the TxSP 324 may not use theencoder parser.

The interleaver 302 interleaves the bits of each stream output from theencoder 300 to change an order of bits therein. The interleaver 302 mayapply the interleaving only when the encoder 300 performs the BCCencoding, and otherwise may output the stream output from the encoder300 without changing the order of the bits therein.

The mapper 304 maps the sequence of bits output from the interleaver 302to constellation points. If the encoder 300 performed LDPC encoding, themapper 304 may also perform LDPC tone mapping in addition to theconstellation mapping.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324may include a plurality of interleavers 302 and a plurality of mappers304 according to a number of spatial streams (NSS) of the transmission.The TxSP 324 may further include a stream parser for dividing the outputof the encoder 300 into blocks and may respectively send the blocks todifferent interleavers 302 or mappers 304. The TxSP 324 may furtherinclude a space-time block code (STBC) encoder for spreading theconstellation points from the spatial streams into a number ofspace-time streams (NSTS) and a spatial mapper for mapping thespace-time streams to transmit chains. The spatial mapper may use directmapping, spatial expansion, or beamforming.

The IFT 306 converts a block of the constellation points output from themapper 304 (or, when MIMO or MU-MIMO is performed, the spatial mapper)to a time domain block (i.e., a symbol) by using an inverse discreteFourier transform (IDFT) or an inverse fast Fourier transform (IFFT). Ifthe STBC encoder and the spatial mapper are used, the IFT 306 may beprovided for each transmit chain.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324may insert cyclic shift diversities (CSDs) to prevent unintentionalbeamforming. The TxSP 324 may perform the insertion of the CSD before orafter the IFT 306. The CSD may be specified per transmit chain or may bespecified per space-time stream. Alternatively, the CSD may be appliedas a part of the spatial mapper.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocksbefore the spatial mapper may be provided for each user.

The GI inserter 308 prepends a GI to each symbol produced by the IFT306. Each GI may include a Cyclic Prefix (CP) corresponding to arepeated portion of the end of the symbol that the GI precedes. The TxSP324 may optionally perform windowing to smooth edges of each symbolafter inserting the GI.

The RF transmitter 342 converts the symbols into an RF signal andtransmits the RF signal via the antenna 352. When the TxSP 324 performsa MIMO or MU-MIMO transmission, the GI inserter 308 and the RFtransmitter 342 may be provided for each transmit chain.

FIG. 3B illustrates components of a wireless device configured toreceive data according to an embodiment, including a Receiver (Rx) SPU(RxSP) 326, an RF receiver 344, and an antenna 354. In an embodiment,the RxSP 326, RF receiver 344, and antenna 354 may correspond to thereceiving SPU 226, the RF receiver 244, and an antenna of the antennaunit 250 of FIG. 2, respectively.

The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316,a demapper 314, a deinterleaver 312, and a decoder 310.

The RF receiver 344 receives an RF signal via the antenna 354 andconverts the RF signal into symbols. The GI remover 318 removes the GIfrom each of the symbols. When the received transmission is a MIMO orMU-MIMO transmission, the RF receiver 344 and the GI remover 318 may beprovided for each receive chain.

The FT 316 converts each symbol (that is, each time domain block) into afrequency domain block of constellation points by using a discreteFourier transform (DFT) or a fast Fourier transform (FFT). The FT 316may be provided for each receive chain.

When the received transmission is the MIMO or MU-MIMO transmission, theRxSP 326 may include a spatial demapper for converting the respectiveoutputs of the FTs 316 of the receiver chains to constellation points ofa plurality of space-time streams, and an STBC decoder for despreadingthe constellation points from the space-time streams into one or morespatial streams.

The demapper 314 demaps the constellation points output from the FT 316or the STBC decoder to bit streams. If the received transmission wasencoded using the LDPC encoding, the demapper 314 may further performLDPC tone demapping before performing the constellation demapping.

The deinterleaver 312 deinterleaves the bits of each stream output fromthe demapper 314. The deinterleaver 312 may perform the deinterleavingonly when the received transmission was encoded using the BCC encoding,and otherwise may output the stream output by the demapper 314 withoutperforming deinterleaving.

When the received transmission is the MIMO or MU-MIMO transmission, theRxSP 326 may use a plurality of demappers 314 and a plurality ofdeinterleavers 312 corresponding to the number of spatial streams of thetransmission. In this case, the RxSP 326 may further include a streamdeparser for combining the streams output from the deinterleavers 312.

The decoder 310 decodes the streams output from the deinterleaver 312 orthe stream deparser. In an embodiment, the decoder 312 includes an FECdecoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

The RxSP 326 may further include a descrambler for descrambling thedecoded data. When the decoder 310 performs the BCC decoding, the RxSP326 may further include an encoder deparser for multiplexing the datadecoded by a plurality of BCC decoders. When the decoder 310 performsthe LDPC decoding, the RxSP 326 may not use the encoder deparser.

Before making a transmission, wireless devices such as wireless device200 will assess the availability of the wireless medium using ClearChannel Assessment (CCA). If the medium is occupied, CCA may determinethat it is busy, while if the medium is available, CCA determines thatit is idle.

The PHY entity for IEEE Std 802.11 is based on Orthogonal FrequencyDivision Multiplexing (OFDM) or Orthogonal Frequency Division MultipleAccess (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA iscapable of transmitting and receiving Physical Layer Protocol Data Units(PPDUs) that are compliant with the mandatory PHY specifications. A PHYspecification defines a set of Modulation and Coding Schemes (MCS) and amaximum number of spatial streams. Some PHY entities define downlink(DL) and uplink (UL) Multi-User (MU) transmissions having a maximumnumber of space-time streams (STS) per user and employing up to apredetermined total number of STSs.

FIG. 4 illustrates Inter-Frame Space (IFS) relationships. FIG. 4illustrates a Short IFS (SIFS), a Point Coordination Function (PCF) IFS(PIFS), a Distributed Coordination Function (DCF) IFS (DIFS), and anArbitration IFSs corresponding to an Access Category (AC) ‘i’ (AIFS[i]).FIG. 4 also illustrates a slot time.

A data frame is used for transmission of data forwarded to a higherlayer. The WLAN device transmits the data frame after performing backoffif a DIFS has elapsed during which DIFS the medium has been idle.

A management frame is used for exchanging management information, whichis not forwarded to the higher layer. Subtype frames of the managementframe include a beacon frame, an association request/response frame, aprobe request/response frame, and an authentication request/responseframe.

A control frame is used for controlling access to the medium. Subtypeframes of the control frame include a request to send (RTS) frame, aclear to send (CTS) frame, and an acknowledgement (ACK) frame.

When the control frame is not a response frame of another frame, theWLAN device transmits the control frame after performing backoff if aDIFS has elapsed during which DIFS the medium has been idle. When thecontrol frame is the response frame of another frame, the WLAN devicetransmits the control frame after a SIFS has elapsed without performingbackoff or checking whether the medium is idle.

A WLAN device that supports a Quality of Service (QoS) functionality(that is, a QoS station) may transmit the frame after performing backoffif an AIFS for an associated access category (AC), (AIFS[AC]), haselapsed. When transmitted by the QoS station, any of the data frame, themanagement frame, and the control frame which is not the response framemay use the AIFS[AC] of the AC of the transmitted frame.

A WLAN device may perform a backoff procedure when the WLAN device thatis ready to transfer a frame finds the medium busy. In addition, a WLANdevice operating according to the IEEE 802.11n and 802.11ac standardsmay perform the backoff procedure when the WLAN device infers that atransmission of a frame by the WLAN device has failed.

The backoff procedure includes determining a random backoff timecomposed of N backoff slots, each backoff slot having a duration equalto a slot time and N being an integer number greater than or equal tozero. The backoff time may be determined according to a length of aContention Window (CW). In an embodiment, the backoff time may bedetermined according to an AC of the frame. All backoff slots occurfollowing a DIFS or Extended IFS (EIFS) period during which the mediumis determined to be idle for the duration of the period.

When the WLAN device detects no medium activity for the duration of aparticular backoff slot, the backoff procedure shall decrement thebackoff time by the slot time. When the WLAN determines that the mediumis busy during a backoff slot, the backoff procedure is suspended untilthe medium is again determined to be idle for the duration of a DIFS orEIFS period. The WLAN device may perform transmission or retransmissionof the frame when the backoff timer reaches zero.

The backoff procedure operates so that when multiple WLAN devices aredeferring and execute the backoff procedure, each WLAN device may selecta backoff time using a random function, and the WLAN device selectingthe smallest backoff time may win the contention, reducing theprobability of a collision.

FIG. 5 illustrates a Carrier Sense Multiple Access/Collision Avoidance(CSMA/CA) based frame transmission procedure for avoiding collisionbetween frames in a channel according to an embodiment. FIG. 5 shows afirst station STA1 transmitting data, a second station STA2 receivingthe data, and a third station STA3 that may be located in an area wherea frame transmitted from the STA1, a frame transmitted from the secondstation STA2, or both can be received. The stations STA1, STA2, and STA3may be WLAN devices.

The STA1 may determine whether the channel is busy by carrier sensing.The STA1 may determine the channel occupation based on an energy levelin the channel or an autocorrelation of signals in the channel, or maydetermine the channel occupation by using a network allocation vector(NAV) timer.

After determining that the channel is not used by other devices (thatis, that the channel is IDLE) during a DIFS (and performing backoff ifrequired), the STA1 may transmit a Ready-To-Send (RTS) frame to thesecond station STA2. Upon receiving the RTS frame, after a SIFS thesecond station STA2 may transmit a Clear-To-Send (CTS) frame as aresponse of the RTS frame. If Dual-CTS is enabled and the second stationSTA2 is an AP, the AP may send two CTS frames in response to the RTSframe: a first CTS frame in the legacy non-HT format, and a second CTSframe in the HT format.

When the third station STA3 receives the RTS frame, it may set a NAVtimer of the third station STA3 for a transmission duration ofsubsequently transmitted frames (for example, a duration of SIFS+CTSframe duration+SIFS+data frame duration+SIFS+ACK frame duration) usingduration information included in the RTS frame. When the third stationSTA3 receives the CTS frame, it may set the NAV timer of the thirdstation STA3 for a transmission duration of subsequently transmittedframes using duration information included in the CTS frame. Uponreceiving a new frame before the NAV timer expires, the third stationSTA3 may update the NAV timer of the third station STA3 by usingduration information included in the new frame. The third station STA3does not attempt to access the channel until the NAV timer expires.

When the STA1 receives the CTS frame from the second station STA2, itmay transmit a data frame to the second station STA2 after SIFS elapsesfrom a time when the CTS frame has been completely received. Uponsuccessfully receiving the data frame, the second station STA2 maytransmit an ACK frame as a response of the data frame after SIFSelapses.

When the NAV timer expires, the third station STA3 may determine whetherthe channel is busy using the carrier sensing. Upon determining that thechannel is not used by other devices during a DIFS after the NAV timerhas expired, the third station STA3 may attempt to access the channelafter a contention window according to a backoff process elapses.

When Dual-CTS is enabled, a station that has obtained a transmissionopportunity (TXOP) and that has no data to transmit may transmit aCF-End frame to cut short the TXOP. An AP receiving a CF-End framehaving a Basic Service Set Identifier (BSSID) of the AP as a destinationaddress may respond by transmitting two more CF-End frames: a firstCF-End frame using Space Time Block Coding (STBC) and a second CF-Endframe using non-STBC. A station receiving a CF-End frame resets its NAVtimer to 0 at the end of the PPDU containing the CF-End frame.

FIG. 5 shows the second station STA2 transmitting an ACK frame toacknowledge the successful reception of a frame by the recipient.

The PHY entity for IEEE Std 802.11 is based on Orthogonal FrequencyDivision Multiplexing (OFDM) or Orthogonal Frequency Division MultipleAccess (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA iscapable of transmitting and receiving PHY Protocol Data Units (PPDUs)that are compliant with the mandatory PHY specifications.

A PHY entity may provide support for 20 MHz, 40 MHz, 80 MHz, and 160 MHzcontiguous channel widths and support for an 80+80 MHz non-contiguouschannel width. Each channel includes a plurality of subcarriers, whichmay also be referred to as tones.

A PHY entity may define fields denoted as Legacy Signal (L-SIG), SignalA (SIG-A), and Signal B (SIG-B) within which some necessary informationabout PHY Service Data Unit (PSDU) attributes are communicated. Forexample, a High Efficiency (HE) PHY entity may define an L-SIG field, anHE-SIG-A field, and an HE-SIG-B field.

The descriptions below, for sake of completeness and brevity, refer toOFDM-based 802.11 technology. Unless otherwise indicated, a stationrefers to a non-AP HE STA, and an AP refers to an HE AP.

In the IEEE Std 802.11ac, SIG-A and SIG-B fields are called VHT SIG-Aand VHT SIG-B fields. Hereinafter, IEEE Std 802.11ax SIG-A and SIG-Bfields are respectively referred to as HE-SIG-A and HE-SIG-B fields.

FIG. 6A illustrates an HE PPDU 600 according to an embodiment. Atransmitting station generates the HE PPDU frame 600 and transmits it toone or more receiving stations. The receiving stations receive, detect,and process the HE PPDU frame 600.

The HE PPDU frame 600 includes a Legacy Short Training Field (L-STF)field 602, a Legacy (i.e., a Non-High Throughput (Non-HT)) Long TrainingField (L-LTF) 604, a Legacy Signal (L-SIG) field 606, which togethercomprise a legacy preamble 601 and a Repeated L-SIG field (RL-SIG) 608.The L-STF 604 of the HE PPDU has a periodicity of 0.8 μs with 10periods.

The HE PPDU frame 600 also includes an HE-SIG-A field 610, an optionalHE-SIG-B field 612, an HE-STF 614, an HE-LTF 616, and an HE-Data field618.

The legacy preamble 601, the RL-SIG field 608, the HE-SIG-A field 610,and the HE-SIG-B field 612 when present, comprise a first part of the HEPPDU frame 600. In an embodiment, the first part of the HE PPDU frame600 is decoded using a 64-element Discrete Fourier Transform (DFT),having a basic subcarrier spacing of 312.5 KHz.

The HE-SIG-A field 610 is duplicated on each 20 MHz segment after thelegacy preamble to indicate common control information. The HE-SIG-Afield 610 includes a plurality of OFDM HE-SIG-A symbols 620 each havinga duration (including a Guard Interval (GI)) of 4 μs. A number of theHE-SIG-A symbols 620 in the HE-SIG-A field 610 is determined as either 2or 4 depending on a type of the HE PPDU 600.

The HE-SIG-B field 612 is included in Multi-User (MU) PPDU(s). TheHE-SIG-B field 612 includes a plurality of OFDM HE-SIG-B symbols 622each having a duration including a Guard Interval (GI) of 4 μs. Inembodiments, Single User (SU) PPDUs, Tigger-based PPDUs, or both do notinclude the HE-SIG-B field 612. A number of the HE-SIG-B symbols 622 inthe HE-SIG-B field 612 is indicated by N_(HESIGB) in HE-SIG-A and isvariable.

When the HE PPDU 600 has a bandwidth of 40 MHz or more, the HE-SIG-Bfield 612 may be transmitted in first and second HE-SIG-B channels 1 and2. The HE-SIG-B field in the HE-SIG-B channel 1 is referred to as theHE-SIG-B1 field, and the HE-SIG-B field in the HE-SIG-B channel 2 isreferred to as the HE-SIG-B2 field. The HE-SIG-B1 field and theHE-SIG-B2 field are communicated using different 20 MHz bandwidths ofthe HE PPDU 600, and may contain different information. Within thisdocument, the term “HE-SIG-B field” may refer to an HE-SIG-B field of a20 MHz PPDU, or to either or both of an HE-SIG-B1 field or HE-SIG-B2field of a 40 MHz or more PPDU.

An HE-STF 614 of a non-trigger-based PPDU has a periodicity of 0.8 μswith 5 periods. A non-trigger-based PPDU is a PPDU that is not sent inresponse to a trigger frame. An HE-STF 614 of a trigger-based PPDU has aperiodicity of 1.6 μs with 5 periods. Trigger-based PPDUs include ULPPDUs sent in response to respective trigger frames.

The HE-LTF 616 includes one or more OFDM HE-LTF symbols 626 each havinga duration of 12.8 μs plus a Guard Interval (GI). The HE PPDU frame 600may support a 2×LTF mode and a 4×LTF mode. In the 2×LTF mode, an HE-LTFsymbol 626 excluding a Guard Interval (GI) is equivalent to modulatingevery other tone in an OFDM symbol of 12.8 μs excluding the GI, and thenremoving the second half of the OFDM symbol in a time domain. A numberof the HE-LTF symbols 626 in the HE-LTF field 616 is indicated byN_(HELTF), and is equal to 1, 2, 4, 6, or 8.

The HE-Data field 618 includes one or more OFDM HE-Data symbols 628 eachhaving a duration of 12.8 μs plus a Guard Interval (GI). A number of theHE-Data symbols 628 in the HE-Data field 618 is indicated by N_(DATA)and is variable.

FIG. 6B shows a Table 1 indicating additional properties of the fieldsof the HE PPDU frame 600 of FIG. 6A, according to an embodiment.

The descriptions below, for sake of completeness and brevity, refer toOFDMA-based 802.11 technology. Unless otherwise indicated, a stationrefers to a non-AP HE STA, and an AP refers to an HE AP.

Embodiments include a station of an HE WLAN system, wherein the stationmaintains two NAV values. The station maintain an Intra-BSS NAVNAV_(intra-BSS) managed according to frames that are identified asintra-BSS frames, and an Inter-BSS NAV NAV_(inter-BSS) managed accordingto frames that are identified as inter-BSS frames or that cannot bedetermined to be intra-BSS or inter-BSS frames.

The Inter-BSS NAV NAV_(inter-BSS) may on occasion be controlled by anintra-BSS frame that cannot be identified as an intra-BSS frame, and asa result there may be some unintended procedures that cause the HE WLANto operate less efficiently than otherwise would be the case.

The distributed nature of channel access network such as IEEE 802.11WLANs makes the carrier sense mechanism important for reducing a numberof collision occurring in the WLAN. The physical carrier sense of oneSTA is responsible for detecting the transmissions of other STAs. But itmay be impossible to detect every single case in some circumstance. Forexample, a first STA that is a distance away from a second STA may seethe medium as idle even though the second STA (known as the “hiddennode”) is transmitting to an AP, and as a result the first STA may begintransmitting to the AP. The transmissions of the first and second STAsmay then collide at the AP, causing one or both transmissions to fail.

A NAV (Network Allocation Vector) is used in the IEEE 802.11 standardsto overcome this “hidden node” problem by providing a “virtual carriersense” capability. However, as the IEEE 802.11 standard evolves toinclude multiple users' simultaneous transmission/reception scheduledwithin a BSS (such as UL/DL multi-user (MU) transmission performed in acascaded manner), it may be advantageous to use a modified or newlydefined mechanism for virtual carrier sense.

As used herein, an MU transmission refers to transmissions in whichmultiple frames are transmitted to or from multiple STAs simultaneouslyusing different resources. Examples of different resources includedifferent frequency resources in an OFDMA transmission and differentspatial streams in an MU MIMO transmission. DL OFDMA transmissions, DLMU-MIMO transmissions, UL OFDMA transmissions, and UL MU-MIMOtransmissions are examples of MU transmissions.

As used herein, a transmission or frame is targeted to a station whenthe transmission or frame includes, in a receiver address field, areceiver address of the station.

As used herein, a 2.4 GHz band may be an IEEE Std 802.11 2.4 GHzband/channel center frequency, including frequencies between 2.4 and 2.5GHz. A frequency or channel being “2.4 GHz” or “in 2.4 GHz” may refer tothe frequency or channel being in the 2.4 band.

As used herein, a 5 GHz band may be an IEEE Std 802.11 5 GHzband/channel center frequency including frequencies between 5 and 5.3GHz. A frequency or channel being “5 GHz” or “in 5 GHz” may refer to thefrequency or channel being in the 5 GHz band.

IEEE 802.11ax supports features such as new CCA levels and deferralrules to improve overlapping BSS (OBSS) operation in dense environments.A station determines, using a BSS Color field in an HE-SIG-A field or aMAC address in a MAC header, whether a detected frame is an inter-BSSframe (i.e. a frame transmitted by a device in a different BSS than theone the station is associated with) or an intra-BSS frame (i.e. a frametransmitted by a device in a same BSS as the one the station isassociated with).

When the detected frame is an inter-BSS frame, under specific condition,the CCA uses an OBSS_PD threshold that is greater than the minimumreceive sensitivity level to determine whether the medium is busy. Whenan inter-BSS PPDU is received and has a signal level below the OBSS_PDthreshold, and no other CCA indication indicates a BUSY channel, thenthe station determines that the medium is available for use.

Based on percentage of time within a measurement window that the APsensed the medium was busy by physical CCA or by NAV, the AP maybroadcast a BSS Load element in a beacon frame or Probe frame toindicate the current station population and traffic levels of the BSScontrolled by the AP. Using this information, stations can determine toassociate with the AP broadcasting a low percentage of channelutilization. Depending on the definition of the medium as busy in 11axwith a Spatial Reuse (SR) mechanism, legacy stations may suffer aperformance loss because of misleading load information from APs.

In an HE WLAN being developed by the IEEE 802.11 Task Group axstandardization body, more aggressive channel access is being providedfor. The more aggressive channel access is provided by increasing a CCAthreshold value to increase system throughput. However, increasing theCCA threshold value may result in more frequent packet collisions anddegradation of a Quality of Service (QoS) of packet delivery. This isparticularly true if a first station assesses a wireless medium anddetects a frame that occupies the wireless medium from or to a secondstation within the same BSS that the first station is associated with(that is, if the medium is occupied by an intra-BSS frame relative tothe first station). In this case, even if the CCA threshold value isincreased and the first station initiates a transmission to an AP of theBSS, the transmission will not be successful because the AP is currentlyin the middle of transmission or reception with other stations (e.g.,the second station). Accordingly, a modified CCA threshold value doesnot alter throughput relative to intra-BSS communications. However, thisis not the case when the medium is occupied by an inter-BSS frame.

In light of this, CCA related information or spatial reuse relatedinformation may be indicated in the physical layer header of a framesuch that any station that identifies a start of a frame can utilizethis information in deciding whether to adjust a CCA threshold value.For example, the station may determine a CCA threshold to use accordingto whether information in a frame indicates the frame is an inter-BSSframe or an intra-BSS frame.

An example of an indication of spatial reuse information in a physicallayer header is a Color field of a frame. The Color field is a (partial)BSS identifier/information of a transmitter that the frame wastransmitted by. When a station identifies a start of a frame whenassessing a wireless medium, the station may check the Color field ofthe frame. If the Color field information is the same with the Color ofthe station (indicating that the transmitter of the frame has a highprobability of being associated with the same BSS as the station) thestation assesses the wireless medium as BUSY. However, if the Colorfield information is different from the Color of the station, thestation compares the received signal strength with a first threshold(e.g., an Overlapped BSS Packet Detection (OBSS_PD) threshold), andassesses the wireless medium as BUSY only if the received signalstrength is above the first threshold.

FIG. 7 illustrates a BSS Load element 700, according to an embodiment.In order to assist a station in an OBSS area in determining which BSS toassociate with, an AP may transmit the BSS Load element 700 in a Beaconframe or a Probe frame. The BSS Load element 700 indicates the currentstation population and traffic levels of its BSS.

The BSS Load element 700 includes an Element Identifier (ID) 702occupying one octet and having a value of eleven, a Length field 704occupying one octet and having a value of five, a Station Count field706 occupying two octets, a Channel Utilization field 708 occupying 1octet, and an Available Admission Capacity field 710 occupying twooctets.

The Station Count 706 has a value interpreted as an unsigned integerthat indicates the total number of stations currently associated withthe BSS.

The Channel Utilization field is defined as the percentage of time,linearly scaled with 255 representing 100%, that the AP sensed themedium was busy, as indicated by either the physical or virtual carriersense (CS) mechanism, and determined as described below.

The Available Admission Capacity field 710 corresponds to remainingamount of medium time available via explicit admission control.

FIG. 8 illustrates an unassociated station 842 in an OBSS area 840. FIG.8 includes a first BSS 800 and a second BSS 820. The first BSS 800includes a first AP 802 (AP1), a first station 804 (STA1), and a secondstation 806 (STA2). The second BSS 820 includes a second AP 822 (AP2)and a third station 824 (STA3).

The first station STA1 and the unassociated station 842 are both locatedin the OBSS area 840. Stations in the OBSS area 840 can receivetransmissions from both the first AP AP1 and the second AP AP2, and cansend transmissions to both the first AP AP1 and the second AP AP2.Stations in the OBSS area 840 share the medium.

The first AP AP1 transmits a first Beacon or Probe frame 844, includinga first BSS Load element, that is received by the unassociated station842. The second AP AP2 transmits a second Beacon or Probe frame 846,including a second BSS Load element, that is received by theunassociated station 842.

If a value of the first BSS Load element is less than a value of thesecond BSS load element, the unassociated station 842 may determine thatassociation with the first AP AP1 will give better throughput for theunassociated station 842 than association with the second AP AP2 would.

Embodiments relate to how a Channel Utilization field value of a BSSLoad element should be calculated in the presence of inter-BSStransmissions, such as how the second AP AP2 of FIG. 8 calculates thevalue of the Channel Utilization field of the second BSS Load Elementwhen the second AP AP2 receives one or more inter-BSS frame 834 from thefirst station STA1, as well as transmitting one or more intra-BSS frame826 to the third station STA3 and receiving one or more intra-BSS frames828 from the third station STA3. Given the new Spatial Reuse (SR)mechanism that is intend to increase system throughput by providing moreaggressive channel access, especially in an OBSS area, channel busy time(and therefore Channel Utilization) may be different depending on how itis measured.

FIG. 9 illustrates a measurement of a channel busy time of an inter-BSSframe 902 according to an embodiment. In the embodiment, an OBSS PacketDetection (OBSS_PD) threshold is −72 dBm, whereas a legacy packetdetection threshold may be, for example, −79 dBm or −82 dBm. In theexample, the inter-BSS frame 902 has a received signal strength betweenthe OBSS_PD threshold and the legacy threshold and is identifiable as aninter-BSS frame by an HE device.

After an initial packet detection delay D1 (such as 4 μsec), a non-HEdevice would sense the inter-BSS frame 902 as occupying the channel forthe duration D4, corresponding to a remaining duration of the inter-BSSframe 902 after the packet detection delay D1. The non-HE device is notable to distinguish between intra-BSS and inter-BSS frames.

An HE device using an SR procedure would identify the inter-BSS frame902 as an inter-BSS frame after a second duration D2 when the inter-BSSframe 902 is an HE frame including a Color field. The HE device usingthe SR procedure would identify the inter-BSS frame 902 as an inter-BSSframe after a third duration D3 when the inter-BSS frame 902 is anLegacy frame having a MAC address that does not correspond to a deviceassociated with the BSS of the device receiving the inter-BSS frame 902.Because the inter-BSS frame 902 has a received signal strength less thanthe OBSS_PD threshold, the HE device using an SR procedure sees itsmedium as occupying the channel for only the second or third durationsD2 or D3.

Because the non-HE device sees the inter-BSS frame 902 as occupying thechannel for the longer duration D4, the non-HE device has feweropportunities to use the channel in the presence of the inter-BSS frame902 than an the HE device using the SR procedure.

As a result, if the second AP AP2 of FIG. 8 uses the second and thirddurations D2 and D3 of the SR procedure, whichever duration isapplicable, to determine an SR-enabled channel busy time, the channelbusy time determined by the second AP AP2 will be less than a channelbusy time determined by a non-HE station under the same circumstances.

For example, the second AP AP2 may determine an SR-enabled channel busytime of 30% under circumstances where a non-HE device determines achannel busy time of 50%. At the same time, the first AP AP1 maydetermine an SR-enabled channel busy time of 10% under circumstanceswhere a non-HE device determines a channel busy time of 70%. Theseillustrative channel busy times may be due to transmissions involvingdevices in the OBSS area 840 that are not shown in FIG. 8.

In an embodiment wherein the first and second APs AP1 and AP2 reporttheir respective SR-enabled channel busy times as the BSS Load elementChannel Utilization value, the unassociated station 842 in FIG. 8 willreceive BSS Load element Channel Utilization values corresponding to 10%and 30%, respectively, from the first and second APs AP1 and AP2.

The unassociated station 842 may then determine to associate with thefirst AP AP1. However, when the unassociated station 842 is a non-HEstation, the unassociated station 842 can expect to see a 70% busychannel upon associating with the first AP AP1, instead of the 50% busychannel the unassociated non-HE station 842 would have seen if it hadassociated with the second AP AP2. As a result, the performance of theunassociated station 842 may be decreased by its choice of which AP toassociate with when the unassociated station 842 is a non-HE device,which is unfair to non-HE devices.

In an embodiment, an additional Channel Utilization field consideringthe SR mechanism (SR Channel Utilization) is broadcast in addition tothe (legacy) Channel Utilization field. In an embodiment, the SR ChannelUtilization is indicated in a new BSS Load element. Non-HE devices woulduse the value in the (legacy) Channel Utilization field, and HE deviceswould use the value in the SR Channel Utilization field.

For example, in FIG. 8 the first AP AP1 would broadcast a first BSS Loadelement indicating a Channel Utilization of 70% and also broadcast afirst SR enabled BSS Load element indicating an SR Channel Utilizationof 10%. The second AP AP2 would broadcast a second BSS Load elementindicating a Channel Utilization of 50% and also broadcast a second SRenabled BSS Load element indicating a Channel Utilization of 30%. As aresult, HE stations may determine to associate with the first AP AP1 butlegacy (non-HE) stations may determine to associate with the second APAP2.

However, it may require undesirable cost or complexity for an AP tosense both the legacy and the SR-enabled medium states together within ameasurement window.

In another embodiment, the percentage of time indicated in the ChannelUtilization field corresponds to a percentage of time that the AP sensedthe medium as busy within the measurement window based on only SRenabled capability with either physical or virtual carrier sense. SRenabled capability means the AP senses the medium as busy by followingthe mechanism of SR defined in 11ax.

FIG. 10 illustrates sensing the medium as busy based on only the SRenabled capability. After an initial packet detection delay D1 (such as4 μsec), an HE device using an SR procedure would identify the inter-BSSframe 1002 as an inter-BSS frame after a second duration D2 when theinter-BSS frame 1002 is an HE frame including a Color field. The HEdevice using the SR procedure would identify the inter-BSS frame 1002 asan inter-BSS frame after a third duration D3 when the inter-BSS frame1002 is an Legacy frame having a MAC address that does not correspond toa device associated with the BSS of the device receiving the inter-BSSframe 1002. Because the inter-BSS frame 1002 has a received signalstrength less than the OBSS_PD threshold, the HE device using an SRprocedure sees its medium as occupying the channel for only the secondor third durations D2 or D3.

Because this Channel Utilization field in BSS Load element is newlydesigned to give proper information only for 11ax STAs, legacy ChannelUtilization could be opted out from Beacon frame and Probe frame suchthat legacy STAs are not allowed to refer to the Channel Utilizationinformation before determining to associate with the AP which shouldprovide better throughput.

In another embodiment, the percentage of time indicated in the ChannelUtilization field corresponds to a percentage of time that the AP sensedthe medium as busy within the measurement window based on only SRdisabled capability with either physical or virtual carrier sense. SRdisabled capability means the AP senses the medium as busy as if SRmechanism is not allowed to measure the medium.

FIG. 11 illustrates sensing the medium as busy based on only SR disabledcapability. After an initial packet detection delay D1 (such as 4 μsec),an HE device using an SR procedure may identify the inter-BSS frame 1102as an inter-BSS frame after a second duration D2 when the inter-BSSframe 1102 is an HE frame including a Color field. The HE device usingthe SR procedure would identify the inter-BSS frame 1102 as an inter-BSSframe after a third duration D3 when the inter-BSS frame 1102 is anLegacy frame having a MAC address that does not correspond to a deviceassociated with the BSS of the device receiving the inter-BSS frame1102. For the purpose of performing a transmission, the HE deviceconsiders the medium available after the second or third duration D2 orD2.

However, for purposes of calculating the Channel Utilization based ononly SR disabled capability, the HE device using an SR procedure seesits medium as occupying the channel for the entire fourth duration D4.

FIG. 12 further illustrates a Spatial Reuses operation of theembodiment. A first duration D1 after reception of a first frame 1202,an AP detects the channel as busy. A second duration D2 after the firstduration D1, the AP determines that the first frame 1202 is an inter-BSSframe using Color information in the first frame 1202. The AP thencontinues to sense the medium as busy for the channel utilizationcalculation, but because the received signal strength of the frame first1202 is less than the OBSS_PD threshold, stops considering the mediumbusy for purposes of determining whether to transmit.

As a result, the AP starts transmitting a second frame 1204 while thefirst frame 1202 is still being detected. The AP senses the medium asbusy for utilization calculation throughout the durations of the firstframe 1202 and the second frame 1204, as indicated by a fifth durationD5.

In the example of FIG. 8 in this embodiment, the first AP AP1 wouldbroadcast a first BSS Load element indicating a Channel Utilization of70% and the second AP AP2 would broadcast a second BSS Load elementindicating a Channel Utilization of 50%.

For non-HE stations, the information in Channel Utilization field isexact as it is an exact ratio of channel utilization for that AP. For11ax (HE) stations, which can achieve better throughput by using the SRmechanism to access the medium when receiver power is lower than theOBSS_PD threshold, the HE station can expect the channel to be at leastas available as is indicated in the Channel Utilization field.

The unassociated station 842, regardless of whether it is an HE stationor not, may then determine to associate with the second AP AP2, and canexpect to see a no more than 50% busy channel.

In embodiments, an AP can provide both legacy (non-HE) stations and 11ax(HE) stations with reasonable BSS load information so as to increase theprobability of achieving a high throughput.

Unlike for DL MU-MIMO as used in Very High Throughput (VHT) WLANsaccording to an IEEE Std 802.11ac standard, a WLAN according to an IEEE802.11ax standard (hereinafter, an HE WLAN) may require more protectionmechanisms for MU transmission.

One reason is that the operation scenario for an HE WLAN is different:for example, HE WLANs are intended to operate in denser wirelessenvironments, and to provide outdoor support. Also, the coverage of aBSS of an HE WLAN may be larger compared to a BSS of a VHT WLAN. Thesefactors encourage the use of more robust protection mechanisms.

Another reason is that an HE WLAN supports not only DL MU transmissionbut also UL MU transmission. In the case of UL MU transmission, asframes transmitted from each station are larger, the HE WLAN requiresmore protection for stations which are close to each transmitting orreceiving station.

Another reason is that in an HE WLAN, an AP may exercise more control ofthe medium through increased use of a scheduled access mechanism, whichmay lead to more frequent use of OFDMA transmissions, MU-MIMOtransmissions, or both.

UL MU PPDUs (whether MU-MIMO, OFDMA, or both) are sent in response to aTrigger frame sent by the AP. The Trigger frame may have enoughstation-specific information and assigned resource units to identify thestations which are supposed to transmit UL MU PPDUs.

The Trigger frame is used to allocate resource for UL MU transmissionand to solicit an UL MU transmission after the PPDU that carries theTrigger frame. The Trigger frame also carries other information that isrequired by the responding stations to perform the UL MU transmissions.

FIG. 13 illustrates a frame format for a Trigger frame 1300 suitable foruse in an HE WLAN, according to an embodiment. A value of ReceiverAddress (RA) field 1306 of the Trigger frame 1300 is the address of arecipient station or a broadcast address corresponding to one or morerecipient stations. A value of a TA field 1308 of the Trigger frame 1300is an address of the station transmitting the Trigger frame 1300.

A Common Info field 1310 of the Trigger frame 1300 includes thefollowing subfields:

-   -   A Trigger Type subfield 1322 that indicates a type of the        Trigger frame 1300. Depending on the type of the Trigger frame        1300, the Trigger frame 1300 can include an optional        Type-specific Common Info field 1352 and (in each Per User Info        field(s) 1312-1 to 1312-n) optional Type-specific Per User Info        fields 1376. Table 3 of FIG. 15 shows an encoding of the Trigger        Type subfield 1322 for valid Trigger Types.    -   A Length subfield 1324 that indicates the value of an L-SIG        Length field of an HE trigger-based PPDU transmitted in response        to the Trigger frame 1300.    -   A Cascade Indication subfield 1326 that when set to 1 indicates        that a subsequent Trigger frame follows the current Trigger        frame, and that otherwise has a value of 0.    -   A Carrier Sense (CS) Required subfield 1328. The CS Required        subfield 1328 being set to 1 indicates that station(s)        identified in the Per User Info field(s) 1312-1 to 1312-n of the        Trigger frame 1300 are required to use Energy Detect (ED) to        sense the medium and to consider the medium state and a NAV in        determining whether to respond to the Trigger frame 1300. The CS        Required subfield being set to 0 indicates that the station(s)        identified in the Per User Info field(s) 1312-1 to 1312-n are        not required to consider the medium state or the NAV in        determining whether to respond to the Trigger frame 1300.    -   A CP and LTF Type subfield 1332 that indicates a CP and an        HE-LTF type of the HE trigger-based PPDU transmitted in response        to the Trigger frame 1300. The CP and LTF field encoding is        shown in Table 2 of FIG. 14 (CP and LTF field encoding).    -   An HE-SIG-A Reserved subfield 1348 that indicates contents of an        HE-SIG-A field of the HE trigger-based PPDU transmitted in        response to the Trigger frame 1300. All values in the HE-SIG-A        Reserved subfield 1348 are set to 1.    -   A Spatial Reuse (SR) subfield 1346, described below.

Each of the Per User Info fields 1312-1 to 1312-n includes the followingsubfields:

-   -   A User Identifier subfield 1362 indicating an Association        Identifier (AID) of a station allocated a Resource Unit (RU) in        which to transmit one or more MPDU(s) in the HE trigger-based        PPDU transmitted in response to the Trigger frame 1300.    -   An RU Allocation subfield 1364 indicating an RU to be used to        transmit the HE trigger-based PPDU of the station identified by        User Identifier subfield 1362. The first bit of the RU        Allocation subfield 1364 indicates whether the allocated RU is        located in a primary or non-primary 80 MHz. The mapping of the        subsequent seven bits indices of the RU Allocation subfield 1364        to the RU allocation is shown in Table 4 of FIG. 16.    -   A Coding Type subfield 1366 indicating a coding type of the HE        trigger-based PPDU transmitted in response to the Trigger frame        1300 of the station identified by the User Identifier subfield        1362, and set to 0 for BCC and to 1 for LDPC.    -   An MCS subfield 1368 indicating an MCS of the HE trigger-based        PPDU transmitted in response to the Trigger frame 1300 by the        station identified by User Identifier field 1362.    -   A Dual Carrier Modulation (DCM) subfield 1370 indicating dual        carrier modulation of the HE trigger-based PPDU transmitted in        response to the Trigger frame 1300 by the station identified by        User Identifier field 1362. A value of 1 indicates that the HE        trigger-based PPDU shall use DCM, and a value of 0 indicates        that it shall not.    -   A Spatial Stream (SS) Allocation subfield 1372 indicating        spatial streams of the HE trigger-based PPDU transmitted in        response to the Trigger frame 1300 by the station identified by        User Identifier field 1362.

A Padding field 1314 extends the frame length of the Trigger frame 1300to give the recipient stations more time to prepare their respectiveresponses.

Stations in an HE WLAN perform a CCA before responding to the Triggerframe 1300 when the CS Required indication 1328 in a Trigger frame 1300indicates that it is required, and may not perform the CCA when the CSRequired indication 1328 indicates it is not required. As a resultSpatial Reuse (SR) transmissions (that is, transmissions from stationsin Overlapping BSS (OBSS) areas that are performed at the same time asother transmissions within the overlapped BSSs) may affect UL MUtransmission. It is because given the HE format of an OBSS Triggerframe, stations may be allowed to start a SR transmission before the endof the Trigger frame when SR condition met. So the OBSS station shallindicate the medium as BUSY for the length of the Trigger frame which isHE SU PPDU format or HE extended range SU PPDU when the SR field in theHE-SIG-A of the Trigger frame is set to a specific value.

To increase system throughput, the IEEE 802.11 Task Group ax hasprovided for more aggressive channel access in an HE WLAN by increasinga CCA threshold value. However, increasing the CCA threshold value mayresult in more frequent packet collision and degradation of a Quality ofService (QoS) of a packet delivery. Especially, if a station assesses awireless medium and a frame that occupies the wireless medium is to orfrom stations of the same BSS that the station is associated with (thatis, if the medium is occupied by an intra-BSS frame), then even if theCCA threshold value is increased and the station initiates atransmission to an AP of the BSS, the transmission will may beunsuccessful because the AP may be currently in the middle oftransmission or reception with other stations.

In light of this, CCA related information or spatial reuse relatedinformation may be indicated in the physical layer header of a framesuch that any station that identifies a start of a frame can utilizethis information in deciding whether to adjust a CCA threshold value.

An example of an indication of spatial reuse information in a physicallayer header is a Color field of a frame. The Color field includes(partial) BSS information of a transmitter that the frame wastransmitted by.

FIG. 17 illustrates a process 1700 for determining whether to perform anSR transmission based on an OBSS_PD threshold level, according to anembodiment. The process 1700 may be performed by an HE station in anOBSS area.

At S1702, a station identifies a start of a frame when assessing awireless medium when receiving a PPDU.

At S1704, the process 1700 checks a Color field of the frame. If theColor field information is the same as the Color of the station(indicating that the transmitter of the frame has a high probability ofbeing associated with the same BSS as the station) the process 1700proceeds to S1706; otherwise when the Color field information isdifferent from the Color of the station, the process 1700 proceeds toS1708.

At S1706 process 1700 sets or updates a value of an intra-BSS NAVaccording to information in the received frame, and assesses thewireless medium as BUSY. The process 1700 then ends.

At S1708, since the Color field information is different from the Colorof the station, the process 1700 compares a received signal strength(RSSI) value with a value of a first threshold (e.g., an Overlapping BSSPacket Detection (OBSS_PD) threshold). When the RSSI value is greaterthan the OBSS_PD threshold value, the process 1700 proceeds to S1710;otherwise the process 1700 proceeds to S1712.

At S1710, the process 1700 sets or updates an inter-BSS NAV according toinformation in the received frame, and assesses the wireless medium asBUSY.

At S1712, since the RSSI value is below the OBSS_PD threshold value, thestations shall ignore NAV and, when the medium condition indicates IDLEas a channel sensing result, the stations resumes a backoff countdownprocess (such as a backoff procedure described with reference to FIG. 4,above) after an xIFS period (e.g. SIFS, DIFS, or EIFS) to be ready foran SR transmission.

This OBSS_PD threshold level mechanism corresponds to a receive power ofa frame from an OBSS station (that is, from a station other than astation in the same BSS as the receiving station). Receiving the frame,the receiving station measures receive power. When measured receivepower is lower than the OBSS-PD threshold, the station determines amedium to be IDLE for purposes of initiating an SR transmission.

FIGS. 18A and 18B illustrate an SR transmission according to anembodiment. FIG. 18A shows a first BSS 1800 and a second BSS 1810 havingan OBSS area 1820. The first BSS 1800 includes a first station 1804(STA1) and a second station 1802 (STA2). The second station STA2 is anAP. The second BSS 1810 includes a third station 1812 (STA3) and afourth station 1814 (STA4).

As shown in FIG. 18B, the second station STA2 transmits a Trigger frame1806 to the first station STA1. In response, the first station STA1transmits an UL MU PPDU 1808 to the second station STA2 in UL MU PPDUtransmission 1808A. The transmission of the UL MU PPDU 1808 by the firststation STA1 also results in an (unintended) interference transmission1808B to the third station STA3.

The third station STA3 can initiate a SR transmission when a backoffcount reach down to 0 when 1) a received frame is an inter-BSS PPDUwhose Color information or Address information does not match to myBSSID information and 2) a receive power (e.g. RSSI_(ULPPUD@STA3)) of theinter-BSS PPDU is smaller than a OBSS_PD threshold level.

As a result, because the received interference transmission 1808Bincludes an inter-BSS frame and the receive power RSSI_(ULPPUD@STA3) ofthe interference transmission 1808B is less that the OBSS_PD level, thethird station STA3 may transmit a PPDU 1816 to the fourth station STA4while the UL MU PPDU 1808 is being transmitted by the first stationSTA1.

While the example shows the transmission of the Trigger frame 1806 fromthe second station STA2 to the first station STA1, embodiments are notlimited thereto, and another type of frame may be substituted for theTrigger frame 1806.

In addition to the OBSS_PD threshold mechanism above, OpportunisticAdaptive CCA (OA-CCA) may be used to provide more aggressive use of themedium by SR transmissions.

The OA-CCA mechanism operates according to an interference level causedby an SR transmission. When receiving an inter-BSS frame from an OBSSstation, the receiving station determines a transmit power for SRtransmissions according to an estimated interference level to beaffected to the receiving OBSS station. When the station's transmitpower is lower than the transmit power that would produce theinterference level to be virtually affected to the receiving OBSSstation, the station determines a medium to be IDLE up to the end of theframe.

FIGS. 19A and 19B illustrate an operation of an OA-CCA mechanism,according to an embodiment. FIG. 19A shows a first BSS 1900 and a secondBSS 1910 having an OBSS area 1920. The first BSS 1900 includes a firststation 1904 (STA1) and a second station 1902 (STA2). The second stationSTA2 is an AP. The second BSS 1910 includes a third station 1912 (STA3)and a fourth station 1914 (STA4).

As shown in FIG. 19B, the second station STA2 transmits a Trigger frame1906 to the first station STA1 in Trigger frame transmission 1906A. Thetransmission of the Trigger frame 1906 by the second station STA2 alsoresults in a (unintended) first interference transmission 1906B to thethird station STA3.

In response to the Trigger frame 1906, the first station STA1 transmitsan UL MU PPDU 1908 to the second station STA2 in a UL MU PPDUtransmission 1908A. The transmission of the UL MU PPDU 1908 by the firststation STA1 also results in an (unintended) second interferencetransmission 1908B to the third station STA3.

The third station STA3 detects two valid OBSS (that is, inter-BSS) PPDUsin a row. The third station STA3 measures a received signal strength(RSSI_(trigger frame@STA3)) of the first inter-BSS PPDU (here, theTrigger frame 1906) carried by the first interference transmission 1906Bfrom the second station STA2. Receiving the first inter-BSS PPDU in thefirst interference transmission 1906B which contains the indicationrequesting to defer the SR transmission to the end of the firstinter-BSS PPDU regardless of SR conditions met when 1906B is the Triggerframe, the third station STA3 defers any spatial reuse transmissionsuntil after the end of the first inter-BSS PPDU.

When the third station STA3 receives the second inter-BSS PPDU (the ULMU PPDU 1908, transmitted in response to the Trigger frame 1906, andcarried in the second interference transmission 1908B), the thirdstation STA3 obtains Spatial Reuse Parameters (SRPs) from an HE-SIG-Afield of the UL MU PPDU 1908. Once the SRPs are obtained, the thirdstation STA3 can initiate when a certain SR condition is met, during theremainder of the UL PPDU duration, an SR transmission of a PPDU 1916using a transmission power of TX-Power_(STA3).

A value of an SRP in the HE-SIG-A field of the UL MU PPDU 1908 isobtained by copying an SRP value from the Trigger frame 1906. The valueof the SRP corresponds to a transmit power TX_PWR_(STA2) of secondstation STA2 that transmitted the Trigger frame 1906 plus an AcceptableReceiver Interference level ARI_(STA2) of the second station STA2:SRP=TX_PWR _(STA2) +ARI _(STA2)  Equation 1In an embodiment, the Acceptable Receiver Interference level ARI_(STA2)of the second station STA2 may depend on the MCS used by a transmission.

The transmission power TX-Power_(STA3) used by the third station STA3must be less than SRP−RSSI_(trigger frame@STA3):TX-Power_(STA3) <SRP−RSSI_(trigger frame@STA3)  Equation 2Combining Equations 1 and 2 produces:TX-Power_(STA3) <TX_PWR _(STA2) +ARI_(STA2)−RSSI_(trigger frame@STA3)  Equation 3

Since the TX_PWR_(STA2)−RSSI_(trigger frame@STA3) is substantially equalto the pass loss Pass_LOSS_(STA2) _(_) _(STA3) between STA2 and STA3, athird interference transmission 1916B in FIG. 19A generated by the thirdstation STA3 using transmission power TX-Power_(STA3) has a receivedpower less than the Acceptable Receiver Interference level ARI_(STA2) ofthe second station STA2 when the third interference transmission 1916Barrives at the second station STA2:TX-Power_(STA3)−Pass_Loss_(STA2) _(_) _(STA3) <ARI _(STA2)  Equation 4

In this document, the Spatial Reuse Parameter (SRP) field and theSpatial Reuse (SR) field mean the same and are used interchangeably.

For a trigger-based PPDU that is an UL PPDU, the four 4-bit SR fields ofan HE SIG-A field of the UL PPDU are given values as follows accordingto the operating bandwidth of the UL PPDU:

-   -   For a 20 MHz operating bandwidth, one SR field corresponds to        the entire 20 MHz (the other 3 fields indicate identical        values).    -   For a 40 MHz operating bandwidth, two SR fields respectively        correspond to the two 20 MHz bandwidths of the operating        bandwidth, and the other 2 fields have identical values.    -   For an 80 MHz operating bandwidth, the four SR fields        respectively correspond to the four 20 MHz bandwidths of the        operating bandwidth.    -   For a 160 MHz operating bandwidth, the four SR fields        respectively correspond to the four 40 MHz bandwidths of the        operating bandwidth.    -   For an 80+80 MHz operating bandwidth, the four SR fields        respectively correspond to the four 40 MHz bandwidths of the        operating bandwidth.        In an embodiment, each SR field decodes as one of 14 SRP values        corresponding to different power levels, or as SR not allowed,        or as a reserved value.

FIG. 20 illustrates an issue in OA-CCA specifically with regard tooperations in a 2.4 GHz band.

When channels are assigned according to IEEE Std 802.11ac in a 5 GHzband, only restricted contiguous channel utilizations are allowed,except for 80+80 MHz bandwidths. A primary 20 MHz bandwidth, P20, may belocated in any 20 MHz for a 40, 80, or 160 MHz bandwidth. However, oncethe channel for the primary 20 MHz bandwidth is chosen, the channelsused by the secondary 20 MHz bandwidth, secondary 40 MHz bandwidth ifpresent, and secondary 80 MHz bandwidth if present, are determinedentirely by the location of the primary 20 MHz bandwidth.

An HE Trigger-Based PPDU 2002 transmitted by a device in a first BSSBSS1 includes, in an HE-SIG-A field, a Bandwidth indication 2004 andfirst to fourth Spatial Reuse Parameters (SRPs) 2006 to 2012 (SRP1 toSRP4).

When the HE Trigger-Based PPDU 2002 is transmitted by a device in afirst BSS BSS1, the Bandwidth indication 2004 indicates that theoperational bandwidth of the HE Trigger-Based PPDU 2002 is 40 MHz, andaccordingly, the first SRP SRP1 has a first SRP1 value SRP1 ₁ indicatingan SRP of a first primary 20 MHz (P20) bandwidth 2024 and the second SRPSRP2 has a first SRP2 value SRP2 ₁ indicating an SRP of first secondary20 MHz (S20) bandwidth 2026. The first SRP SRP3 and the first SRP SRP4of the HE Trigger-Based PPDU 2002 have values equal to the first SRP1value SRP1 ₁ and the first SRP2 value SRP2 ₁, respectively.

When the HE Trigger-Based PPDU 2002 is transmitted by a device in asecond BSS BSS2, the Bandwidth indication 2004 indicates that theoperational bandwidth of the HE Trigger-Based PPDU 2002 is 40 MHz, andaccordingly, the second SRP SRP1 has a second SRP1 value SRP1 ₂indicating an SRP of a second primary 20 MHz (P20) bandwidth 2014 andthe second SRP SRP2 has a second SRP2 value SRP2 ₂ indicating an SRP ofsecond secondary 20 MHz (S20) bandwidth 2016. The second SRP SRP3 andSRP4 of the HE Trigger-Based PPDU 2002 have values equal to the secondSRP1 and SRP2 values SRP1 ₂ and SRP2 ₂, respectively.

A device (here, the OBSS STA) operating in the 2.4 GHz band andreceiving the HE Trigger-Based PPDU 2002 needs to determine which SRP touse in performing the OA-CCA based transmission. However, theinformation in the HE-SIG-A field of the HE Trigger-Based PPDU 2002 onlyindicates the SRP based on the relative positions of the 20 MHzbandwidths. Because there is no absolute frequency information in theHE-SIG-A field of the HE Trigger-Based PPDU 2002, the device cannotdetermine whether to use the first SRP SRP2 or the second SRP SRP1 whenperforming the OA-CCA. In the example, when the device receives the HETrigger-Based PPDU 2002 from the first BSS BSS1, an OA-CCA transmissionby the device shall use the first SRP SRP2 value SRP2 ₁ that indicatesan SRP of the first secondary 20 MHz (S20) bandwidth 2026 in performingthe OA-CCA, but the device cannot make that determination using theinformation shown in the HE Trigger-Based PPDU 2002.

FIG. 21 shows another example of an issue in OA-CCA. An HE Trigger-BasedPPDU 2102 includes, in an HE-SIG-A field, a Bandwidth indication 2104and first to fourth SRPs 2106 to 2112 (SRP1 to SRP4). In the example ofFIG. 21, a device in a first BSS BSS1 has an operational bandwidth of160 MHz, and a device in a second BSS BSS2 has an operational bandwidthof 80+80 MHz.

The device of the first BSS BSS1 operates in a first primary 40 MHz(P40) bandwidth 2124, a first secondary 40 MHz (S40) bandwidth 2126, afirst third 40 MHz bandwidth 2128, and a first fourth 40 MHz bandwidth2130. The first third 40 MHz bandwidth 2128 and the first fourth 40 MHzbandwidth 2130 make up a first secondary 80 MHz (S80) bandwidth.

When a HE Trigger-Based PPDU 2102 is from the first BSS BSS1, the firstto fourth SRPs SRP1 to SRP4 respectively indicate a first SRP1 valueSRP1 ₁ of a first third 40 MHz bandwidth 2128, a first SRP2 value SRP2 ₁of a first fourth 40 MHz bandwidth 2130, a first SRP3 value SRP3 ₁ of afirst Primary 40 MHz bandwidth 2124, and a first SRP4 value SRP4 ₁ of afirst secondary 40 MHz bandwidth 2126.

The device of the second BSS BSS2 operates in a second primary 40 MHz(P40) bandwidth 2114, a second secondary 40 MHz (S40) bandwidth 2116, asecond third 40 MHz bandwidth 2118, and a second fourth 40 MHz bandwidth2120. The second third 40 MHz bandwidth 2118 and the second fourth 40MHz bandwidth 2120 make up a second secondary 80 MHz (S80) bandwidth.

When a HE Trigger-Based PPDU 2102 is from the second BSS BSS2, the firstto fourth SRPs SRP1 to SRP4 respectively indicate a second SRP1 valueSRP1 ₂ of a second primary 40 MHz bandwidth 2114, a second SRP2 valueSRP2 ₂ of a second secondary 40 MHz bandwidth 2116, a second SRP3 valueSRP3 ₂ of a second third 40 MHz bandwidth 2118, and a second SRP4 valueSRP4 ₂ of a second fourth 40 MHz bandwidth 2120.

Depending on where a HE Trigger-Based PPDU 2102 comes from, which isunknown to a device (here, an OBSS STA), the device cannot determinewhich SR fields need to be used for SR transmission using OA-CCA. Itcould be the third and fourth SRPs SRP3 and SRP4 respectively includingthe first SRP3 and SRP4 values SRP3 ₁ and SRP4 ₁ when received from thefirst BSS BSS1 or it could be the first and second SRPs SRP1 and SRP2respectively including the second SRP1 and SRP2 values SRP1 ₂ and SRP2 ₂when received from the second BSS BSS2.

FIG. 22 shows another example of an issue in OA-CCA. An HE Trigger-BasedPPDU 2202 includes, in an HE-SIG-A field, a Bandwidth indication 2204and first to fourth SRPs 2206 to 2212 (SRP1 to SRP4). In the example ofFIG. 22, a device in a first BSS BSS1 has an operational bandwidth of80+80 MHz, and a device in a second BSS BSS2 has an operationalbandwidth of 80+80 MHz.

The device of the first BSS BSS1 operates in a first primary 40 MHz(P40) bandwidth 2224, a first secondary 40 MHz (S40) bandwidth 2226, afirst third 40 MHz bandwidth 2228, and a first fourth 40 MHz bandwidth2230. The first third 40 MHz bandwidth 2228 and the first fourth 40 MHzbandwidth 2230 make up a first secondary 80 MHz (S80) bandwidth.

When a HE Trigger-Based PPDU 2204 is from the first BSS BSS1, the firstto fourth SRPs SRP1 to SRP4 respectively indicate a first SRP1 valueSRP1 ₁ of a first third 40 MHz bandwidth 2228, and a first SRP2 valueSRP2 ₁ of a first fourth 40 MHz bandwidth 2230, a first SRP3 value SRP3₁ of a first primary 40 MHz bandwidth 2224, a first SRP4 value SRP4 ₁ ofa first secondary 40 MHz bandwidth 2226.

A device of the second BSS BSS2 operates in a second primary 40 MHz(P40) bandwidth 2214, a second secondary 40 MHz (S40) bandwidth 2216, asecond third 40 MHz bandwidth 2218, and a second fourth 40 MHz bandwidth2220. The second third 40 MHz bandwidth 2218 and the second fourth 40MHz bandwidth 2220 make up a second secondary 80 MHz (S80) bandwidth.

When the HE Trigger-Based PPDU 2204 is from the second BSS BSS2, thefirst to fourth SRPs SRP1 to SRP4 respectively indicate a second SRP1value SRP1 ₂ of a second primary 40 MHz bandwidth 2214, a second SRP2value SRP2 ₂ of a second secondary 40 MHz bandwidth 2216, a second SRP3value SRP3 ₂ of a second third 40 MHz bandwidth 2218, and a second SRP4value SRP4 ₂ of a second fourth 40 MHz bandwidth 2220.

Depending on where the HE Trigger-Based PPDU 2204 comes from, which isunknown to a device, the device cannot determine which SR fields need tobe used for SR transmission using OA-CCA. It could be the second SRPsSRP1 and SRP2 or it could be the first SRPs SRP3 and SRP4.

Embodiments include methods to indicate exact channel position in orderto determine which SR parameter values among the multiple SR fields areused for each 20 MHz or 40 MHz channel depending on an operating channelbandwidth (e.g. a 20 MHz/40 MHz/80 MHz/160 MHz/80+80 MHz channelbandwidth).

In an embodiment, in a Trigger-based PPDU transmitted in response toTrigger frame, an HE-SIG-A field includes multiple 4-bit SR fields(totaling 16 bits) and a frequency location field which corresponds to achannel location. The frequency location field may also be referred toas a channel information field.

-   -   Values of the SR field in HE-SIG-A which copied from values of        the SR field in Trigger frame indicate the condition on whether        SR transmission is allowed on each 20 MHz or 40 MHz channel.    -   The frequency location field is a frequency location of a        channel.

The multiple 4-bit SR fields are signaled as indicated below:

-   -   For a 20 MHz operating bandwidth, one SR field corresponds to        the entire 20 MHz (the other 3 fields indicate identical        values).    -   For a 40 MHz operating bandwidth, two SR fields respectively        correspond to the two 20 MHz bandwidths of the operating        bandwidth, and the other 2 fields have identical values.    -   For an 80 MHz operating bandwidth, the four SR fields        respectively correspond to the four 20 MHz bandwidths of the        operating bandwidth.    -   For a 160 MHz or 80+80 MHz operating bandwidth, the four SR        fields respectively correspond to the four 40 MHz bandwidths of        the operating bandwidth.

The frequency location field indicates a frequency location of an i-thSR field. The i-th SR field may be a first SR field.

-   -   For 20 MHz, the frequency location field indicates a location of        a 20 MHz bandwidth having the SR parameter indicated by the i-th        SR field among the multiple SR fields.    -   For 40 MHz, the frequency location field indicates a location of        a 20 MHz bandwidth having the SR parameter indicated by the i-th        SR field among the multiple SR fields.    -   For 80 MHz, the frequency location field indicates a location of        a 20 MHz bandwidth having the SR parameter indicated by the i-th        SR field among the multiple SR fields.    -   For 160 MHz and 80+80 MHz, the frequency location field        indicates a location of a 40 MHz bandwidth having the SR        parameter indicated by the i-th SR field among the multiple SR        fields

The i-th SR field could be the first, second, third, or fourth 20 MHz or40 MHz bandwidth in a frequency domain. In an embodiment, the frequencylocation is a channel number. In an embodiment, a size of the frequencylocation field is 8 bits.

Returning to the examples of FIGS. 21 and 22, a first station receives aHE Trigger-Based PPDU frame from the second BSS BSS2, and a frequencylocation field of a HE-SIG-A field of the frame indicates a location ofthe bandwidth corresponding to the first SRP SRP1 (that is, the firstSRP SRP1 corresponding to the primary 40 MHz channel of the second BSSBSS2, and indicating the second SRP1 value SRP1 ₂), the location beingthe same as a location used by the primary 40 MHz channel of the firststation (the 40 MHZ bandwidth 2114 in FIG. 21, and the 40 MHz 2214 inFIG. 22). The location of the bandwidth corresponding to the second SRPSRP2 of the received frame can be determined by the first station fromthe location of the bandwidth corresponding to the first SRP SRP1 of thereceived frame. The first station doesn't have any information onfrequency location for the second SRPs SRP3 value SRP3 ₂ to SRP4 valueSRP4 ₂.

-   -   For 20 MHz, the first station could initiate SR transmission up        to 20 MHz when SR conditions of OA-CCA, determined using the        second SRP1 value SRP1 ₂ of the received frame from the second        BSS BSS2, on the 20 MHz are met.    -   For 40 MHz, the first station could initiate SR transmission up        to 40 MHz when SR conditions of OA-CCA, determined using the        second SRP1 and SRP2 values SRP1 ₂ and SRP2 ₂ of the received        frame from the second BSS BSS2, on each 20 MHz are met.    -   For 80 MHz, the first station could initiate SR transmission up        to 80 MHz when SR conditions of OA-CCA, determined using the        second SRP1, SRP2, SRP3 and SRP4 values SRP1 ₂, SRP2 ₂, SRP3 ₂        and SRP4 ₂ of the received frame from the second BSS BSS2, on        each 20 MHz are met.    -   For 160/80+80 MHz,        -   If a value in the frequency location field of the i-th 20            MHz doesn't match with the first devices i-th 20 MHz            location wherein the value in the frequency location field            of the i-th 20 MHz is meant to belong to the first device's            first 80 MHz, the first station could initiate SR            transmission up to 160 MHz when SR conditions of OA-CCA on            each 40 MHz are met.        -   Otherwise, the first station could initiate SR transmission            up to 80 MHz which includes its i-th 20 MHz when SR            conditions of OA-CCA on each 40 MHz are met.

FIG. 23 illustrates an example of fields in an HE-SIG-A field 2300according to an embodiment. The fields contains first, second, third,and fourth SR fields 2302, 2304, 2306, and 2308, and a frequencylocation field 2310. The frequency location field 2310 indicates afrequency location of the 1^(st) 20 MHz (for 20, 40, and 80 MHZbandwidths) or 40 MHz (for 160 or 80+80 MHz bandwidths) bandwidthcorresponding to the first SR field 2302.

FIG. 24 illustrates an example of SR operation in 2.4 GHz band accordingto an embodiment.

The HE Trigger-based PPDU 2402 includes bandwidth information indicating40 MHz operation and a frequency information field indicating channel kas the 1^(st) 20 MHz bandwidth corresponding to a second primary 20 MHzchannel 2404. A device, which knows the channels it uses for a firstprimary and secondary 20 MHz channels 2414 and 2416 are channels k−1 andk, respectively, determines using the frequency information field of theHE Trigger-based PPDU 2402 that the first SR field SRP1 of the HETrigger-based PPDU 2402 (indicating the second SRP1 value SRP1 ₂)includes SR information for channel k and should be used when performingSR transmissions.

FIG. 25 illustrates another example of SR operation according to anembodiment. A first device in a first BSS BSS1 operates using a 160 MHzbandwidth having a first primary 40 MHz (P40) bandwidth 2514 in achannel k+2, a first secondary 40 MHz (S40) bandwidth 2516 in a channelk+3, a first tertiary (i.e. third) 40 MHz bandwidth 2518 in a channel k,and a first quaternary (i.e. fourth) 40 MHz bandwidth 2520 in a channelk+1. The first tertiary 40 MHz bandwidth 2518 and first quaternary 40MHz bandwidth 2520 comprise a first secondary 80 MHz (S80) bandwidth.

A second device operates in a second BSS BSS2 using an 80+80 MHzbandwidth having a second primary 40 MHz (P40) bandwidth 2504 in achannel k+2, a second secondary 40 MHz (S40) bandwidth 2506 in a channelk+3, a second tertiary 40 MHz bandwidth 2508 in a channel higher thank+3, and a second quaternary 40 MHz bandwidth 2510 in a channel higherthan k+3. The second tertiary 40 MHz bandwidth 2508 and secondquaternary 40 MHz bandwidth 2510 comprise a second secondary 80 MHz(S80) bandwidth.

A HE Trigger-based PPDU 2502 includes bandwidth information indicating80+80 MHz operation and a frequency information field indicating channelk+2 as the 1^(st) 40 MHz bandwidth corresponding to the second primary40 MHz channel 2504. A device, which knows the channels it uses for theoperating channels 2514 to 2520 are channels k+2, k+3, k, and k+1,respectively, determines using the frequency information field of the HETrigger-based PPDU 2502 that the first SR field SRP1 of the HETrigger-based PPDU 2502 includes SR information (the second SRP1 valueSRP1 ₂) for the channel k+2 and that the second SR field SRP2 of the HETrigger-based PPDU 2502 includes SR information (the second SRP2 valueSRP2 ₂) for the channel k+3. As a result, the device concludes that thesecond SRP1 and SRP2 values SRP1 ₂ and SRP2 ₂ should be used whenperforming SR transmissions.

FIG. 26 illustrates another example of SR operation according to anembodiment. A first device in a first BSS BSS1 operates using a 80+80MHz bandwidth having a first primary 40 MHz (P40) bandwidth 2618 in achannel k, a first secondary 40 MHz (S40) bandwidth 2620 in a channelk+1, a first tertiary 40 MHz bandwidth 2614 in a channel j, and a firstquaternary 40 MHz bandwidth 2616 in a channel j+1, where j+1 is lessthan k. The first tertiary 40 MHz bandwidth 2614 and first quaternary 40MHz bandwidth 2616 comprise a first secondary 80 MHz (S80) bandwidth.

A second device in a second BSS BSS2 operates using an 80+80 MHzbandwidth having a second primary 40 MHz (P40) bandwidth 2604 in achannel k, a second secondary 40 MHz (S40) bandwidth 2606 in a channelk+1, a second tertiary 40 MHz bandwidth 2608 in a channel higher thank+1, and a second quaternary 40 MHz bandwidth 2610 in a channel higherthan k+1. The second tertiary 40 MHz bandwidth 2608 and secondquaternary 40 MHz bandwidth 2610 comprise a second secondary 80 MHz(S80) bandwidth.

A HE Trigger-based PPDU 2602 includes bandwidth information and afrequency information field indicating channel k as the 1^(st) 40 MHzbandwidth corresponding to the second primary 40 MHz channel 2604. Adevice, which knows the channels it uses for 2514 to 2620 are channelsk, k+1, j, and j+1, respectively, determines using the frequencyinformation field of the HE Trigger-based PPDU 2602 that the SRP1 of theHE Trigger-based PPDU 2602 includes SR information (the second SRP1value SRP1 ₂) for the channel k and that the SRP2 of the HETrigger-based PPDU 2602 includes SR information (the second SRP2 valueSRP2 ₂) for the channel k+1. As a result, the device concludes that thesecond SRP1 and SRP2 values SRP1 ₂ and SRP2 ₂ should be used whenperforming SR transmissions.

Considering the limited number of bits available in an HE-SIG-A field,adding frequency location field to indicate channel location may beburdensome. Embodiments include methods to keep the combined length ofthe 4-bit SR fields and frequency location field (if any) at a total of16 bits.

In an embodiment, a Trigger-based PPDU transmitted in response to aTrigger frame includes an HE-SIG-A field that includes multiple 4-bit SRfields having a total length of 16 bits. Values of the SR fields in theHE-SIG-A field are values respectively copied from corresponding SRfields in the Trigger frame transmitted by an AP and indicate respectiveconditions under which SR transmissions are allowed on eachcorresponding 20 MHz or 40 MHz channel of an operating bandwidth.

The multiple 4-bit SR fields are signaled as indicated below:

-   -   For a 20 MHz operating bandwidth, one SR field corresponds to        the entire 20 MHz (the other 3 fields indicate identical        values).    -   For a 40 MHz operating bandwidth, two SR fields respectively        correspond to the two 20 MHz bandwidths of the operating        bandwidth, and the other 2 fields have identical values.    -   For an 80 MHz operating bandwidth, the four SR fields        respectively correspond to the four 20 MHz bandwidths of the        operating bandwidth.    -   For a 160 MHz or 80+80 MHz operating bandwidth, the four SR        fields respectively correspond to the four 40 MHz bandwidths of        the operating bandwidth.

In an embodiment, a one-bit field in the HE-SIG-A field differentiatesbetween 160 MHz and 80+80 MHz so that a device may have differentbehavior for each bandwidth.

The embodiment includes addition constraints on the SR field of theHE-SIG-A field that a station may choose when the station cannotdetermine which SR field or fields is or are to be used for SRtransmission in the situations shown in FIGS. 20, 21, and 22.

-   -   For a 40 MHz SR transmission in a 2.4 GHz band, the SR field        with the most conservative value of the first and second SR        fields, respectively corresponding to first and second 20 MHz        bandwidths, (e.g. the minimum value among the first and second        SR fields) is used.    -   For 80+80 MHz SR transmission, the SR field with the most        conservative value of the first and third SR fields,        respectively corresponding to first and third 40 MHz bandwidths,        (e.g. the minimum value among the first and third SR fields) is        used, and the SR field with the most conservative value of the        second and fourth SR fields, respectively corresponding to        second and fourth 40 MHz bandwidths, (e.g. the minimum value        among the second and fourth SR fields) is used

FIGS. 27 and 28 illustrate aspects of the embodiment. FIG. 27illustrates values of SR fields within an HE-SIG-A field of an ULTrigger-based PPDU transmitted from a first BSS in response to a Triggerframe, according to an operational bandwidth of the UL Trigger-basedPPDU. The values of the SR fields are copied from values in SR fields ofthe Trigger frame.

FIG. 28 illustrates the SR values used for SR transmissions by a device,according to an operational bandwidth of a received inter-BSS ULTrigger-based PPDU transmission of an OBSS device. The device receivesthe UL Trigger-based PPDU transmitted from the first BSS and determineswhich SR field(s) is (are) used from the UL Trigger-based PPDU.

FIG. 28 shows that when the second device is performing a 40 MHz SRtransmission in a 2.4 GHz band, the second devices uses a mostconservative value of the SR field 1 and the SR field 2 to performOA-CCA for primary and secondary 20 MHz channels of the 40 MHz SRtransmission. A most conservative value of two SR fields is that valueof the two SR fields that corresponds to a lower allowable transmissionpower for the second device than the other value of the two SR fields.

FIG. 28 shows that when the second device is performing an 80+80 MHz SRtransmission, the second devices uses a most conservative value of theSR field 1 and the SR field 3 to perform OA-CCA for primary and tertiary40 MHz channels of the 80+80 MHz SR transmission, and uses a mostconservative value of the SR field 2 and the SR field 4 to performOA-CCA for secondary and quaternary 40 MHz channels of the 80+80 MHz SRtransmission.

FIG. 29 illustrates aspects of OA_CCA for a 40 MHz transmission having achannel center frequency in a 2.4 GHz band, according to an embodiment.In the example of FIG. 29, a first device in a first BSS BSS1 has anoperational bandwidth of 40 MHz, and a second device in a second BSSBSS2 has an operational bandwidth of 40 MHz. The first device operatesin a first primary 20 MHz (P20) bandwidth 2924 and a first secondary 20MHz (S20) bandwidth 2926. The second device operates in a second primary20 MHz bandwidth 2914 and a second secondary 20 MHz bandwidth 2916.

An HE Trigger-Based PPDU 2902 includes, in an HE-SIG-A field, aBandwidth indication 2904 and first to fourth SRPs 2906 to 2912 (SRP1 toSRP4). When the HE Trigger-Based PPDU 2902 is from the first BSS BSS1,accordingly, the first SRP SRP1 indicates a first SRP1 value SRP1 ₁ of afirst primary 20 MHz (P20) bandwidth 2924 and the second SRP SRP2indicates an a first SRP2 value SRP2 ₁ of first secondary 20 MHz (S20)bandwidth 2926. The third and fourth SRPs SRP3 and SRP4 of the HETrigger-Based PPDU 2902 have values equal to the first and second SRPsSRP1 and SRP2, respectively.

When the HE Trigger-Based PPDU 2902 is from the second BSS BSS2,accordingly, the first SRP SRP1 indicates a second SRP1 value SRP1 ₂ ofa second primary 20 MHz (P20) bandwidth 2914 and the second SRP SRP2indicates an a second SRP2 value SRP2 ₂ of second secondary 20 MHz (S20)bandwidth 2916. The third and fourth SRPs SRP3 and SRP4 of the HETrigger-Based PPDU 2902 have values equal to the first and second SRPsSRP1 and SRP2, respectively.

A device receiving the HE Trigger-Based PPDU 2902 regardless of where itis from determines to use a conservative SRP having a value Min_(SRP1)_(_) ₂ equal to the most conservative of the values of the SRP1 and SRP2received in the HE Trigger-Based PPDU 2902. The device uses theidentical Min_(SRP1) _(_) ₂ as an SRP value when performing OA-CCA foran SR transmission in any of the 20 MHz channels.

FIG. 30 illustrates aspects of OA_CCA for an 80+80 MHz transmission,according to an embodiment. In the example of FIG. 30, a first device ina first BSS BSS1 has an operational bandwidth of 160 MHz, and a seconddevice in a second BSS BSS2 has an operational bandwidth of 80+80 MHz.The first device operates in a first primary 40 MHz (P40) bandwidth3024, a first secondary 40 MHz (S40) bandwidth 3026, a first third 40MHz bandwidth 3028, and a first fourth 40 MHz bandwidth 3030. The firstthird 40 MHz bandwidth 3028 and the first fourth 40 MHz bandwidth 3030make up a first secondary 80 MHz (S80) bandwidth.

The second device operates in a second primary 40 MHz (P40) bandwidth3014, a second secondary 40 MHz (S40) bandwidth 3016, a second third 40MHz bandwidth 3018, and a second fourth 40 MHz bandwidth 3020. Thesecond third 40 MHz bandwidth 3018 and the second fourth 40 MHzbandwidth 3020 make up a second secondary 80 MHz (S80) bandwidth.

An HE Trigger-Based PPDU 3002 includes, in an HE-SIG-A field, aBandwidth indication 3004 and first to fourth SRPs 3006 to 3012 (SRP1 toSRP4). When a HE Trigger-Based PPDU 3002 is from the first BSS BSS1,accordingly, the first to fourth SRPs SRP1 to SRP4 respectively indicatea first SRP1 value SRP1 ₁ of the first third 40 MHz bandwidth 3028, afirst SRP2 value SRP2 ₁ of the first fourth 40 MHz bandwidth 3030, afirst SRP3 value SRP3 ₁ of the first primary 40 MHz bandwidth 3024, anda first SRP4 value SRP4 ₁ of the first secondary 40 MHz bandwidth 3026.When a HE Trigger-Based PPDU 3002 is from the second BSS BSS2,accordingly, the first to fourth SRPs SRP1 to SRP4 respectively indicatea second SRP1 value SRP1 ₂ of the second primary 40 MHz bandwidth 3014,a second SRP2 value SRP2 ₂ of the second secondary 40 MHz bandwidth3016, a second SRP3 value SRP3 ₂ of the second third 40 MHz bandwidth3018, and a second SRP4 value SRP4 ₂ of the second fourth 40 MHzbandwidth 3020.

When a device receives a HE Trigger-Based PPDU 3002, the device candetermine the bandwidth information and SRP values in an HE-SIG-A of theHE Trigger-Based PPDU. The device determines to use a first conservativeSRP having a value Min_(SRP1) _(_) ₃ equal to the most conservative ofthe values of the SRP1 and the SRP3 received in the HE Trigger-BasedPPDU 3002. The device determines to use a second conservative SRP havinga value Min_(SRP2) _(_) ₄ equal to the most conservative of the valuesof the SRP2 and the SRP4 received in the HE Trigger-Based PPDU 3002.

The device uses the Min_(SRP1) _(_) ₃ value for an SRP when performingOA-CCA for an SR transmission in one or more of the first primary 40 MHzbandwidth 3024 and the first third 40 MHz bandwidth 3028, and uses theMin_(SRP2) _(_) ₄ value for an SRP when performing OA-CCA for an SRtransmission in one or more of the first secondary 40 MHz bandwidth 3026and the first fourth 40 MHz bandwidth 3030 when the Trigger-Based PPDU3002 from the first BSS BSS1. However, the device determines to use theMin_(SRP1) _(_) ₃ or MIN_(SRP2) _(_) ₄ wherein the device doesn't needto know which operating band is assigned for the HE Trigger-Based PPDU3002.

As shown in FIGS. 29 and 30, even though a device does not have anyfrequency location information on which SR fields are located on which20 MHz or 40 MHz channels, the embodiment allows that after receivingthe SR fields in an HE-SIG-A field of a received inter-BSS HETrigger-based PPDU, the device may:

-   -   For a 20 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 20 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For a 40 MHz received inter-BSS HE Trigger-based PPDU in a 2.4        GHz band, initiate an SR transmission of up to 20 MHz bandwidth        when SR conditions of OA-CCA on each 20 MHz are met.    -   For an 80 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 80 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For a 160 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 160 MHz bandwidth when SR conditions        of OA-CCA on each 40 MHz are met.    -   For an 80+80 MHz received inter-BSS HE Trigger-based PPDU,        initiate an SR transmission of up to 80 MHz bandwidth when SR        conditions of OA-CCA on each 40 MHz are met.

FIG. 31 illustrates SR field values of a Trigger frame according toanother embodiment. In the embodiment, constraints are placed on thevalues set for the fields 1, 2, 3, and 4 in the Trigger frame when anoperational bandwidth is 40 MHz in a 2.4 GHz band or an operationalbandwidth is 80+80 Mhz.

In Trigger-based PPDU transmitted in response to the Trigger frame, anHE-SIG-A field includes first, second, third, and fourth 4-bit SR fields(totaling 16 bits) having values copied from corresponding SR fields 1,2, 3, and 4, respectively, in the Trigger frame. The values of thefirst, second, third, and fourth SR fields in the Trigger frame indicatethe conditions under which SR transmissions are allowed on respective 20MHz or 40 MHz channels.

The 4-bit SR fields in Trigger frame are determined as indicated below:

-   -   For a 20 MHz operational bandwidth, SR field 1 includes an SRP        value for the 20 MHz bandwidth, and the other three SR fields        indicate values identical to the SR field 1.    -   For a 40 MHz operational bandwidth not in a 2.4 GHz band, SR        fields 1 and 2 include respective SRP values for first and        second 20 MHz bandwidths, and SR fields 3 and 4 include values        identical to the first and second SR fields, respectively.    -   For a 40 MHz operational bandwidth in the 2.4 GHz band, the SR        field 1 has a conservative value appropriate for both the first        and second 20 MHz bandwidths (i.e., a minimum of an SRP value        for the first 20 MHz bandwidth (SRP1) and an SRP value for the        second 20 MHz bandwidth (SRP2)), and SR fields 2, 3, and 4        indicate values identical to the value of the SR field 1.    -   For an 80 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 20 MHz bandwidths.    -   For a 160 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 40 MHz bandwidths.    -   For an 80+80 MHz operational bandwidth, SR field 1 includes a        conservative value appropriate for both the first and third 40        MHz bandwidths (i.e., a minimum of an SRP value for the first 40        MHz bandwidth (SRP1) and an SRP value for the third 40 MHz        bandwidth (SRP3)). SR field 2 includes a conservative value        appropriate for both the second and fourth 40 MHz bandwidths        (i.e., a minimum of an SRP value for the second 40 MHz bandwidth        (SRP2) and an SRP value for the fourth 40 MHz bandwidth (SRP4)).        SR field 3 includes a same value as the value of SR field 1, and        SR field 4 includes a same value as the value of SR field 2.

In this embodiment, in the example of FIG. 29 wherein the BW informationindicating 40 MHz, a device can use any values among the multiple SRfields for any of 20 MHz values because the four SR fields indicateidentical values. The device doesn't need frequency location informationfor the SR fields.

In this embodiment, in the example of FIG. 30 with bandwidth informationindicating 80+80 MHz, the device can use, either the values in SR field1 and SR field 2 or the values in SR field 3 and SR field 4, because SRfields 1 and 3 indicate identical values and SR field 3 and 4 indicateidentical values. The device doesn't need frequency location informationfor the SR fields.

As shown in FIGS. 29 and 30, even though a device does not have anyfrequency location information on which SR fields are located on which20 MHz or 40 MHz channels, the embodiment allows that after receivingthe SR fields in an HE-SIG-A field of a received inter-BSS HETrigger-based PPDU, the device may:

-   -   For a 20 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 20 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For a 40 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 20 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For an 80 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 80 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For a 160 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 160 MHz bandwidth when SR conditions        of OA-CCA on each 40 MHz are met.    -   For an 80+80 MHz received inter-BSS HE Trigger-based PPDU,        initiate an SR transmission of up to 80 MHz bandwidth when SR        conditions of OA-CCA on each 40 MHz are met.

In an embodiment, the Trigger frame includes a 1 bit indication thatdifferentiates between the 160 MHz and the 80+80 MHz cases.

In another embodiment, and HE-SIG-A contains multiple 4-bit SR fieldsand an optional channel information field which corresponds to a channellocation, totaling 16 bits. The SR fields indicates conditions underwhich SR transmission is allowed on respective 20 MHz or 40 MHzchannels. The channel information field indicates a frequency location.

FIG. 32 shows the SR fields and the optional channel information fieldof the HE-SIG-A field for transmissions in a 2.4 GHz band, according toan embodiment. For a 20 MHz operational bandwidth, a first SR field (SRfield 1) indicates an SRP value for the 20 MHz bandwidth, and the otherthree SR fields (SR field 2, 3, and 4) indicate values identical to thefirst SR field. For a 40 MHz operational bandwidth, SR fields 1 and 2include respective SRP values for first and second 20 MHz bandwidths,and the bits that would otherwise convey the SR fields 3 and 4 insteadconvey a channel information field. The channel information fieldindicates a frequency location of a bandwidth corresponding to the SRfield 1 or the SR field 2. In an embodiment, the size of the channelnumber field is eight bits.

FIG. 33 illustrates another embodiment, in which an HE-SIG-A fieldincludes multiple 4-bit SR fields and, for an 80+80 MHz operationalbandwidth, a channel information field corresponding to a channellocation.

The SR fields indicates the condition on whether SR transmission isallowed on respective 20 MHz or 40 MHz channels. The channel informationfield indicates a frequency location. The 4-bit SR fields and thechannel information field are determined as indicated below:

-   -   For a 20 MHz operational bandwidth, SR field 1 includes an SRP        value for the 20 MHz bandwidth, and the other three SR fields        indicate values identical to the first SR field.    -   For a 40 MHz operational bandwidth, SR fields 1 and 2 include        respective SRP values for first and second 20 MHz bandwidths,        and SR fields 3 and 4 include values identical to the first and        second SR fields, respectively.    -   For an 80 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 20 MHz bandwidths.    -   For a 160 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 40 MHz bandwidths.    -   For an 80+80 MHz operational bandwidth, SR field 1 includes an        SRP value appropriate for both the first and third 40 MHz        bandwidths. SR field 2 includes an SRP value appropriate for        both the second and fourth 40 MHz bandwidths. That is, the SRP        values provided in SR fields 1 and 2 for a primary 80 MHz        bandwidth are repeated for a secondary 80 MHz bandwidth. The        channel information field, which occupies bits that would        otherwise be occupied by SR fields 3 and 4, indicates a        frequency location of an 80 MHz bandwidth which doesn't include        the Primary 20 MHz channel. In an embodiment, the frequency        location is indicated using a channel number. In an embodiment,        the size of the channel information field is eight bits.

In an embodiment, the HE-SIG-A field includes a one bit indication thatdifferentiates between the 160 MHz and the 80+80 MHz operationalbandwidths.

Considering the limited room available in the HE-SAG-A field to addfrequency location to indicate channel location (which may require 8bits) in addition to multiple N-bit SR information fields, for 80+80 MHzthe secondary 80 MHz location may not be clear. One of the 4-bit SRfield could be used to provide SRP for the secondary 80 MHz for SRtransmissions.

FIG. 34 illustrates another embodiment, in which an HE-SIG-A fieldincludes multiple 4-bit SR fields (total 16 bits) wherein the SR fieldindicates the condition on whether SR transmission is allowed on each 20MHz or 40 MHz channel.

The SR fields indicates the condition on whether SR transmission isallowed on respective 20 MHz or 40 MHz channels. The channel informationfield indicates a frequency location. The 4-bit SR fields and thechannel information field are determined as indicated below:

-   -   For a 20 MHz operational bandwidth, SR field 1 includes an SRP        value for the 20 MHz bandwidth, and SR fields 1, 2, and 3        indicate values identical to the SR field 1.    -   For a 40 MHz operational bandwidth, SR fields 1 and 2 include        respective SRP values for first and second 20 MHz bandwidths,        and SR fields 3 and 4 include values identical to the SR fields        1 and 2, respectively.    -   For an 80 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 20 MHz bandwidths.    -   For a 160 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 40 MHz bandwidths.    -   For an 80+80 MHz operational bandwidth, SR field 1 includes an        SRP value appropriate for all of the first to fourth 40 MHz        bandwidths, and SR fields 1, 2, and 3 indicate values identical        to the SR field 1. The value of the SR field 1 is a most        conservative value among SR values appropriate for the first to        fourth 40 MHz bandwidths.

In an embodiment, the HE-SIG-A field includes a one bit indication thatdifferentiates between the 160 MHz and the 80+80 MHz operationalbandwidths.

FIG. 35 illustrates another embodiment, in which an HE-SIG-A fieldincludes multiple 4-bit SR fields (totaling 16 bits) wherein the SRfield indicates the condition on whether SR transmission is allowed oneach 20 MHz or 40 MHz channel. The 4-bit SR fields are determined asindicated below:

-   -   For a 20 MHz operational bandwidth, SR field 1 includes an SRP        value for the 20 MHz bandwidth, and SR fields 1, 2, and 3        indicate values identical to the SR field 1.    -   For a 40 MHz operational bandwidth, SR fields 1 and 2 include        respective SRP values for first and second 20 MHz bandwidths,        and SR fields 3 and 4 include values identical to the SR fields        1 and 2, respectively.    -   For an 80 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 20 MHz bandwidths.    -   For a 160 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 40 MHz bandwidths.    -   For an 80+80 MHz operational bandwidth, SR field 1 includes an        SRP value for both the first and third 40 MHz bandwidths. SR        field 2 includes an SRP value for both the second and fourth 40        MHz bandwidths. SR fields 3 and 4 include values identical to        the values of SR fields 1 and 2, respectively.

The HE-SIG-A field further includes a one bit indication thatdifferentiates between the 160 MHz and the 80+80 MHz operationalbandwidths.

When channels are assigned according to IEEE Std 802.11ac, onlyrestricted contiguous channel utilizations are allowed, except for 80+80MHz bandwidths. A primary 20 MHz bandwidth, may be located in any 20 MHzchannel. Once the channel for the primary 20 MHz bandwidth is chosen,the channels used by a secondary 20 MHz bandwidth, a secondary 40 MHzbandwidth, and a secondary 80 MHz bandwidth, if present, are determinedentirely by the location of the primary 20 MHz bandwidth.

Considering UL OFDMA transmissions in an HE WLAN in addition tocoexistence with legacy BSSs supporting narrower bands, thenon-contiguous channel bonding allows data transmission of HE stationson assigned non-contiguous channels which increase the systemefficiency. But allowing every combination of available non-contiguouschannels could be burden because it requires the large number of controlinformation subfield (around 9 bits) in an HE-SIG field and increase thesystem complexity. It is reasonable to give some limitation to thenon-contiguous channel bonding allocation.

FIG. 36 shows an example of an illustrative set of allowed channelbondings which includes the most useful cases which are most likely tooccur. FIG. 36 includes examples of a discontinuous 60 MHz channel 3602,a discontinuous 40 MHz channel 3604, a discontinuous 140 MHz channel3606, and a discontinuous 140 MHz channel 3608.

The discontinuous 60 MHz channel 3602 includes a primary 20 MHzbandwidth 3602A and a secondary 40 MHz bandwidth 3602B.

The discontinuous 40 MHz channel 3602 includes a primary 20 MHzbandwidth 3602A and a right half of a secondary 40 MHz (S40R) bandwidth3602B. Information regarding the primary 20 MHz bandwidth 3602A may beincluded in a first channel of an HE-SIG-B field, and informationregarding the right half of a secondary 40 MHz bandwidth 3602B may beincluded in a second channel of the HE-SIG-B field.

The discontinuous 140 MHz channel 3602 includes a primary 20 MHzbandwidth 3606A, a secondary 40 MHz bandwidth 3606B, and a secondary 80MHz bandwidth 3606C.

The discontinuous 140 MHz channel 3602 includes a primary 20 MHzbandwidth 3608A, a secondary 20 MHz bandwidth 3608B, and a secondary 80MHz bandwidth 3608C.

Given a value in BW field indicating a non-contiguous channel with thefirst 80 MHz case of a discontinuous 60 MHz channel 3602, different 60MHz channels could be virtually assigned depending on the position ofthe Primary 20 MHz channel, as shown in FIGS. 37A and 37B.

FIG. 37A shows an example of a discontinuous 60 MHz channel when aprimary 20 MHz channel is assigned to a lower half of a 40 MHz frequencyblock. FIG. 37B shows an example of a discontinuous 60 MHz channel whena primary 20 MHz channel is assigned to as upper half of a 40 MHzfrequency block.

There may be some ambiguity when it comes to the SR indication rulebetween multiple SR fields above and each 20 MHz of a non-contiguouschannel. In addition, there may need to be a definition of which valuesto set in each of the SR field where the medium is BUSY on secondary 20MHz channels. FIGS. 37A and 37B show the 20 MHz bandwidth being numberedsequentially for the SR fields, without numbering the unused bandwidths.

FIGS. 38A and 38B illustrate another embodiment. In the embodiment ofFIGS. 38A and 38B, the 20 MHz bandwidth being numbered sequentially forthe SR fields, starting with the lowest frequency bandwidth even if itnot used by the discontinuous 60 MHz channel.

In the embodiment, an SR-field comprises multiple SR fields where afirst SR field corresponds to a lowest 20 MHz or 40 MHz channel in afrequency domain depending on a channel bandwidth, wherein an i-th 4-bitSR field indicates a value of SR parameters for an i-th 20 MHz channel.

The first SR field (SR field 1) corresponds to the lowest 20 MHz for an80 MHz channel bandwidth. The first SR field corresponds to the lowest40 MHz for a 160 MHz or 80+80 MHz channel bandwidth.

When a medium of i-th 20 MHz channel is BUSY, the SR field of the i-th20 MHz channel sets a value with reserved or SR-not-allowed.

FIG. 39 illustrates another embodiment, in which an HE-SIG-A fieldincludes two frequency indications for primary and secondary 80 MHzbandwidths of an 80+80 MHz bandwidth. In a Trigger-based PPDUtransmitted in response to a Trigger frame, an HE-SIG-A field includesmultiple 4-bit SR fields (total 16 bits) and two channel informationfield which corresponds to frequency locations of channels. Values ofthe SR fields in HE-SIG-A are copied from values of SR fields in theTrigger frame, and indicate the condition under which SR transmissionsare allowed on each 20 MHz or 40 MHz channel. The channel informationfield includes a frequency location.

The 4-bit SR fields are determined as indicated below:

-   -   For a 20 MHz operational bandwidth, SR field 1 includes an SRP        value for the 20 MHz bandwidth, and SR fields 1, 2, and 3        indicate values identical to the SR field 1.    -   For a 40 MHz operational bandwidth, SR fields 1 and 2 include        respective SRP values for first and second 20 MHz bandwidths,        and SR fields 3 and 4 include values identical to the SR fields        1 and 2, respectively.    -   For an 80 MHz operational bandwidth, SR fields 1, 2, 3, and 4        include respective SRP values for first, second, third, and        fourth 20 MHz bandwidths.    -   For 160 MHz and 80+80 MHz operational bandwidths, SR fields 1,        2, 3, and 4 include respective SRP values for first, second,        third, and fourth 40 MHz bandwidths.

The two channel information fields indicate first frequency locations ofan i-th SR field and second frequency locations of a j-th SR field.

-   -   For a 20 MHz operational bandwidth, the first frequency location        is of a first 20 MHz bandwidth indicated by the i-th SR field        among the SR fields, and the second frequency location is of the        first 20 MHz bandwidth indicated by the j-th SR field among the        SR fields.    -   For a 40 MHz operational bandwidth, the first frequency location        is of a first 20 MHz bandwidth indicated by the i-th SR field        among the SR fields, and the second frequency location is of a        second 20 MHz bandwidth indicated by the j-th SR field among the        SR fields.    -   For an 80 MHz operational bandwidth, the first frequency        location is of a first 20 MHz bandwidth indicated by the i-th SR        field among the SR fields, and the second frequency location is        of a second 20 MHz bandwidth indicated by the j-th SR field        among the SR fields.    -   For 160 MHz and 80+80 MHz operational bandwidths, the first        frequency location is of a first 40 MHz bandwidth indicated by        the i-th SR field among the SR fields, and the second frequency        location is of a second 40 MHz bandwidth indicated by the j-th        SR field among the SR fields.

For 40, 80, 160, and 80+80 MHz operational bandwidth, the values of iand j are not same. The i-th SR field may correspond to the first,second, third, fourth 20 or 40 MHz bandwidth in a frequency domain. Thej-th SR field may correspond to the first, second, third, fourth 20 or40 MHz bandwidth in a frequency domain.

In an embodiment, the first and second frequency locations could beindicated by respective channel numbers.

In an embodiment, the first and second frequency locations could beindicated by an index (or order) of a 20 MHz channel list supported inthe regulatory domain or an index (or order) of an 80 MHz channel listsupported in the regulatory domain.

In respective embodiments, a size of each frequency location field couldbe 2, 3, or 4 bits.

For 160 MHz and 80+80 MHz, the two channel information fields shallrespectively indicate a first frequency location of a first 80 MHzsegment and a second frequency location of a second 80 MHz segment. For40 MHz, the two channel information fields shall respectively indicate afirst frequency location of a first 20 MHz segment and a secondfrequency location of a second 20 MHz segment.

After determining values of SR fields in an HE-SIG-A field of a receivedinter-BSS HE Trigger-based PPDU, a device may:

-   -   For a 20 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 20 MHz bandwidth when SR conditions        of OA-CCA on the 20 MHz are met.    -   For a 40 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 40 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For an 80 MHz received inter-BSS HE Trigger-based PPDU, initiate        an SR transmission of up to 80 MHz bandwidth when SR conditions        of OA-CCA on each 20 MHz are met.    -   For a 160 MHz or 80+80 MHz received inter-BSS HE Trigger-based        PPDU, initiate an SR transmission of up to 160 MHz bandwidth        when SR conditions of OA-CCA on each 40 MHz are met.

As shown in FIG. 40, 80 MHz channelization of a 5 GHz band are definedin the United State wherein channel center frequency indices are 42, 58,106, 122, 138 and 155. In other countries, such as Japan and countriesin Europe, 80 MHz channelization of a 5 GHz band are have channel centerfrequency indices of 42, 58, 106 and 122.

In an embodiment, values of the Frequency Location fields corresponds tothe channel center frequency index of 80 MHz channels. For example, foran 80+80 MHz operational bandwidth, when a value of 0 is assigned to aFrequency Location field corresponding to a first 40 MHz bandwidth, the80 MHz channelization whose channel center frequency index is 42 isassigned for first and second 40 MHz channels of the 80+80 MHzoperational bandwidth.

In an embodiment, the value in Frequency Location corresponds to thenumbering of enumerated 80 MHz from lowest frequency as an example inFIG. 41. For example, for an 80+80 MHz operational bandwidth when valueis set to 0 in the Frequency Location field of a first 40 MHz bandwidth,an 80 MHz channelization having a lowest frequency is assigned first andsecond 40 MHz channels of the 80+80 MHz operational bandwidth.

FIG. 42 illustrates a process 4200 for determining SR fields of aTrigger frame, according to an embodiment. In an embodiment, the process4200 is performed by an AP of an HE WLAN.

At S4202, the process 4200 determines an operating bandwidth. Theoperating bandwidth may be an operating bandwidth of a PPDU transmittedin response to the Trigger frame.

At S4204, the process 4200 determines whether the operating bandwidth isa 40 MHz bandwidth. The process 4200 proceeds to S4230 when theoperating bandwidth is the 40 MHz bandwidth, and otherwise proceeds toS4206.

At S4206, the process 4200 determines whether the operating bandwidth isan 80+80 MHz bandwidth. The process 4200 proceeds to S4210 when theoperating bandwidth is the 80+80 MHz bandwidth, and otherwise proceedsto S4208.

At S4208, the process 4200 determines values in the SR fields of thetrigger frame according to whether the operating bandwidth is 20, 80, or160 MHz. The process 4200 then ends.

At S4210, the process 4200 determines a value in a first SR parameterSRP1 for a primary 40 MHz bandwidth of the operating bandwidth.

At S4212, the process 4200 determines a value in a second SR parameterSRP2 for a secondary 40 MHz bandwidth of the operating bandwidth.

At S4214, the process 4200 determines a value in a third SR parameterSRP3 for a first 40 MHz bandwidth of a secondary 80 MHz bandwidth of theoperating bandwidth.

At S4216, the process 4200 determines a value in a fourth SR parameterSRP4 for a second 40 MHz bandwidth of a secondary 80 MHz bandwidth ofthe operating bandwidth.

At S4218, the process 4200 determines a first conservative SR parameterMin_SRP1 by calculating a minimum of the value of the first SR parameterSRP1 and the value of the third SR parameter SRP3.

At S4220, the process 4200 determines a second conservative SR parameterMin_SRP2 by calculating a minimum of the value of the second SRparameter SRP2 and the value of the fourth SR parameter SRP4.

At S4222, and as illustrated in the “For 80+80 MHz” example of FIG. 31,the process 4200 sets each of a first SR field of a frame (SR field 1)and a third SR field of the frame (SR field 3) according to the value ofthe first conservative SR parameter Min_SRP1, and sets each of a secondSR field of a frame (SR field 2) and a fourth SR field of the frame (SRfield 4) according to the value of the second conservative SR parameterMin_SRP2. The process 4200 then ends.

At S4230, the process 4200 determines a value in a first SR parameterSRP1 for a primary 20 MHz bandwidth of the operating bandwidth.

At S4232, the process 4200 determines a value in a second SR parameterSRP2 for a secondary 20 MHz bandwidth of the operating bandwidth.

At S4234, the process 4200 determines whether the operating bandwidth isin a 2.4 GHz band. The process 4200 proceeds to S4238 when the operatingbandwidth is in the 2.4 GHz band, and otherwise proceeds to S4236.

At S4236, the process 4200 sets each of a first SR field of a frame anda third SR field of the frame according to the value of the first SRparameter SRP1, and sets each of a second SR field of a frame and afourth SR field of the frame according to the value of the second SRparameter SRP2. The process 4200 then ends.

At S4238, the process 4200 determines a conservative SR parameterMin_SRP by calculating a minimum of the value of the first SR parameterSRP1 and the value of the second SR parameter SRP2.

At S4240, and as illustrated in the “For 40 MHz (2.4 GHz only)” exampleof FIG. 31, the process 4200 sets each of the first, second, third, andfourth SR fields of the frame according to the value of the conservativeSR parameter Min_SRP. The process 4200 then ends.

After the process 4200 ends, the AP performed the process 4200 maytransmit the frame including the first to fourth SR fields.

Embodiments enable additional opportunities for Spatial Reuse (SR)transmissions in OBSS regions, thereby increasing system efficiency ofan HE WLAN.

The solutions provided herein have been described with reference to awireless LAN system; however, it should be understood that thesesolutions are also applicable to other network environments, such ascellular telecommunication networks, wired networks, etc.

The above explanation and figures are applied to an HE station, an HEframe, an HE PPDU, an HE-SIG field and the like of the IEEE 802.11axamendment, but they can also applied to a receiver, a frame, PPDU, a SIGfield, and the like of another future amendment of IEEE 802.11.

Embodiments of the present disclosure include electronic devicesconfigured to perform one or more of the operations described herein.However, embodiments are not limited thereto.

Embodiments of the present disclosure may further include systemsconfigured to operate using the processes described herein. The systemsmay include basic service sets (BSSs) such as the BSSs 100 of FIG. 1,but embodiments are not limited thereto.

Embodiments of the present disclosure may be implemented in the form ofprogram instructions executable through various computer means, such asa processor or microcontroller, and recorded in a non-transitorycomputer-readable medium. The non-transitory computer-readable mediummay include one or more of program instructions, data files, datastructures, and the like. The program instructions may be adapted toexecute the processes and to generate and decode the frames describedherein when executed on a device such as the wireless devices shown inFIG. 1.

In an embodiment, the non-transitory computer-readable medium mayinclude a read only memory (ROM), a random access memory (RAM), or aflash memory. In an embodiment, the non-transitory computer-readablemedium may include a magnetic, optical, or magneto-optical disc such asa hard disk drive, a floppy disc, a CD-ROM, and the like.

In some cases, an embodiment of the invention may be an apparatus (e.g.,an AP station, a non-AP station, or another network or computing device)that includes one or more hardware and software logic structure forperforming one or more of the operations described herein. For example,as described above, the apparatus may include a memory unit, whichstores instructions that may be executed by a hardware processorinstalled in the apparatus. The apparatus may also include one or moreother hardware or software elements, including a network interface, adisplay device, etc.

While this invention has been described in connection with what ispresently considered to be practical embodiments, embodiments are notlimited to the disclosed embodiments, but, on the contrary, may includevarious modifications and equivalent arrangements included within thespirit and scope of the appended claims. The order of operationsdescribed in a process is illustrative and some operations may bere-ordered. Further, two or more embodiments may be combined.

What is claimed is:
 1. A method implemented by a station in a wirelesscommunication system, the method comprising: receiving a trigger framesoliciting an uplink frame from an access point; generating the uplinkframe comprising spatial reuse information and bandwidth information ofthe uplink frame, wherein the spatial reuse information comprises fourSpatial Reuse (SR) values, and wherein a bandwidth of the uplink framespans one or more 20 MHz channels; and transmitting the uplink framesolicited by the trigger frame to the access point, wherein each of thefour SR values is determined based on the bandwidth of the uplink frameand a frequency band in which the station operates.
 2. The method ofclaim 1, wherein all of the four SR values have a same value when thebandwidth is 20 MHz.
 3. The method of claim 1, wherein when thebandwidth is 40 MHz, a first SR value and a third SR value apply to afirst 20 MHz channel of the bandwidth, and a second SR value and afourth SR value apply to a second 20 MHz channel of the bandwidth. 4.The method of claim 3, wherein the first SR value is the same as thethird SR value, and the second SR value is the same as the fourth SRvalue.
 5. The method of claim 4, wherein the first SR value is the sameas the second SR value when the station operates in a 2.4 GHz band. 6.The method of claim 1, wherein when the bandwidth is 80 MHz, a first SRvalue applies to a first 20 MHz channel of the bandwidth, a second SRvalue applies to a second 20 MHz channel of the bandwidth, a third SRvalue applies to a third 20 MHz channel of the bandwidth, and a fourthSR value applies to a fourth 20 MHz channel of the bandwidth.
 7. Themethod of claim 1, wherein when the bandwidth is 160 MHz or 80+80 MHz, afirst SR value applies to a first 40 MHz channel of the bandwidth, asecond SR value applies to a second 40 MHz channel of the bandwidth, athird SR value applies to a third 40 MHz channel of the bandwidth, and afourth SR value applies to a fourth 40 MHz channel of the bandwidth. 8.The method of claim 7, wherein the first SR value is the same as thethird SR value when the bandwidth is 80+80 MHz.
 9. The method of claim8, wherein the second SR value is the same as the fourth SR value whenthe bandwidth is 80+80 MHz.
 10. The method of claim 1, wherein each ofthe four SR values has a predetermined value indicating information oftransmit power for a spatial reuse transmission.
 11. The method of claim1, wherein the four SR values are included in the trigger frametransmitted from the access point.
 12. A station in a wirelesscommunication system, the station comprising: a receiver configured toreceive a trigger frame soliciting an uplink frame from an access point;a processor configured to generate the uplink frame comprising spatialreuse information and bandwidth information of the uplink frame, whereinthe spatial reuse information comprises four Spatial Reuse (SR) values,wherein a bandwidth of the uplink frame spans one or more 20 MHzchannels, and wherein each of the four SR values is determined based onthe bandwidth of the uplink frame and a frequency band in which thestation operates; and a transmitter configured to transmit the uplinkframe solicited by the trigger frame to the access point.
 13. Thestation of claim 12, wherein all of the four SR values have a same valuewhen the bandwidth is 20 MHz.
 14. The station of claim 12, wherein whenthe bandwidth is 40 MHz, a first SR value and a third SR value apply toa first 20 MHz channel of the bandwidth, and a second SR value and afourth SR value apply to a second 20 MHz channel of the bandwidth. 15.The station of claim 14, wherein the first SR value is the same as thethird SR value, and the second SR value is the same as the fourth SRvalue.
 16. The station of claim 15, wherein the first SR value is thesame as the second SR value when the station operates in a 2.4 GHz band.17. The station of claim 12, wherein when the bandwidth is 80 MHz, afirst SR value applies to a first 20 MHz channel of the bandwidth, asecond SR value applies to a second 20 MHz channel of the bandwidth, athird SR value applies to a third 20 MHz channel of the bandwidth, and afourth SR value applies to a fourth 20 MHz channel of the bandwidth. 18.The station of claim 12, wherein when the bandwidth is 160 MHz or 80+80MHz, a first SR value applies to a first 40 MHz channel of thebandwidth, a second SR value applies to a second 40 MHz channel of thebandwidth, a third SR value applies to a third 40 MHz channel of thebandwidth, and a fourth SR value applies to a fourth 40 MHz channel ofthe bandwidth.
 19. The station of claim 18, wherein the first SR valueis the same as the third SR value, and the second SR value is the sameas the fourth SR value when the bandwidth is 80+80 MHz.
 20. The stationof claim 12, wherein the four SR values are included in the triggerframe transmitted from the access point.